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Sample records for resistant cobalt alloys

  1. Relaxation resistance of heat resisting alloys with cobalt

    International Nuclear Information System (INIS)

    Borzdyka, A.M.

    1977-01-01

    Relaxation resistance of refractory nickel-chromium alloys containing 5 to 14 % cobalt is under study. The tests involve the use of circular samples at 800 deg to 850 deg C. It is shown that an alloy containing 14% cobalt possesses the best relaxation resistance exceeding that of nickel-chromium alloys without any cobalt by a factor of 1.5 to 2. The relaxation resistance of an alloy with 5% cobalt can be increased by hardening at repeated loading

  2. Heat-Resistance of the Powder Cobalt Alloys Reinforced by Niobium or Titanium Carbide

    Directory of Open Access Journals (Sweden)

    Cherepova, T.S.

    2016-01-01

    Full Text Available The characteristics of heat-resistance of powder cobalt alloys at 1100 °C were investigated. These alloys were developed for the protection of workers banding shelves GTE blades from wear. The alloys were prepared by hot pressing powders of cobalt, chromium, aluminum, iron and niobium or titanium carbides. The values of heat resistance alloys containing carbides between 30 and 70% (vol. depend on the type made of carbide alloys: alloys with titanium carbide superior in heat-resistant alloy of niobium carbide. The most significant factor affecting on the heat-resistant alloys, is porosity: with its increase the parameters decline regardless of the type and content of carbide. The optimum composition of powder heat resisting alloys of titanium carbide with a melting point above 1300 °C were determined for use in the aircraft engine.

  3. Thermal-fatigue and oxidation resistance of cobalt-modified Udimet 700 alloy

    International Nuclear Information System (INIS)

    Bizon, P.T.; Barrow, B.J.

    1986-04-01

    Comparative thermal-fatigue and oxidation resistances of cobalt-modified wrought Udimet 700 alloy (obtained by reducing the cobalt level by direct substitution of nickel) were determined from fluidized-bed tests. Bed temperatures were 1010 and 288 C (1850 and 550 C) for the first 5500 symmetrical 6-min cycles. From cycle 5501 to the 14000-cycle limit of testing, the heating bed temperature was increased to 1050 C (1922 F). Cobalt levels between 0 and 17 wt% were studied in both the bare and NiCrAlY overlay coated conditions. A cobalt level of about 8 wt% gave the best thermal-fatigue life. The conventional alloy specification is for 18.5% cobalt, and hence, a factor of 2 in savings of cobalt could be achieved by using the modified alloy. After 13500 cycles, all bare cobalt-modified alloys lost 10 to 13 percent of their initial weight. Application of the NiCrAlY overlay coating resulted in weight losses of 1/20 to 1/100 of that of the corresponding bare alloy

  4. Assessment of corrosion resistance of cast cobalt- and nickel-chromium dental alloys in acidic environments.

    Science.gov (United States)

    Mercieca, Sven; Caligari Conti, Malcolm; Buhagiar, Joseph; Camilleri, Josette

    2018-01-01

    The aim of this study was to compare the degradation resistance of nickel-chromium (Ni-Cr) and cobalt-chromium (Co-Cr) alloys used as a base material for partial dentures in contact with saliva. Wiron® 99 and Wironit Extra-Hard® were selected as representative casting alloys for Ni-Cr and Co-Cr alloys, respectively. The alloys were tested in contact with deionized water, artificial saliva and acidified artificial saliva. Material characterization was performed by X-ray diffractometry (XRD) and microhardness and nanohardness testing. The corrosion properties of the materials were then analyzed using open circuit potential analysis and potentiodynamic analysis. Alloy leaching in solution was assessed by inductively coupled plasma mass spectrometry techniques. Co-Cr alloy was more stable than the Ni-Cr alloy in all solutions tested. Leaching of nickel and corrosion attack was higher in Ni-Cr alloy in artificial saliva compared with the acidified saliva. The corrosion resistance of the Co-Cr alloy was seen to be superior to that of the Ni-Cr alloy, with the former exhibiting a lower corrosion current in all test solutions. Microstructural topographical changes were observed for Ni-Cr alloy in contact with artificial saliva. The Ni-Cr alloy exhibited microstructural changes and lower corrosion resistance in artificial saliva. The acidic changes did not enhance the alloy degradation. Ni-Cr alloys are unstable in solution and leach nickel. Co-Cr alloys should be preferred for clinical use.

  5. Development of wear-resistant coatings for cobalt-base alloys

    International Nuclear Information System (INIS)

    Cockeram, B.V.

    1999-01-01

    The costs and hazards resulting from nuclear plant radiation exposure with activated cobalt wear debris could potentially be reduced by covering the cobalt-base materials with a wear resistant coating. However, the hardnesses of many cobalt-base wear alloys are significantly lower than conventional PVD hard coatings, and mechanical support of the hard coating is a concern. Four approaches have been taken to minimize the hardness differences between the substrate and PVD hard coating: (1) use a thin Cr-nitride hard coating with layers that are graded with respect to hardness, (2) use a thicker, multilayered coating (Cr-nitride or Zr-nitride) with graded layers, (3) use nitriding to harden the alloy subsurface followed by application of a multilayered coating of Cr-nitride, and (4) use of nitriding alone. Since little work has been done on application of PVD hard coatings to cobalt-base alloys, some details on process development and characterization of the coatings is presented. Scratch testing was used to evaluate the adhesion of the different coatings. A bench-top rolling contact test was used to evaluate the wear resistance of the coatings. The test results are discussed, and the more desirable coating approaches are identified

  6. Corrosion resistance of sodium sulfate coated cobalt-chromium-aluminum alloys at 900 C, 1000 C, and 1100 C

    Science.gov (United States)

    Santoro, G. J.

    1979-01-01

    The corrosion of sodium sulfate coated cobalt alloys was measured and the results compared to the cyclic oxidation of alloys with the same composition, and to the hot corrosion of compositionally equivalent nickel-base alloys. Cobalt alloys with sufficient aluminum content to form aluminum containing scales corrode less than their nickel-base counterparts. The cobalt alloys with lower aluminum levels form CoO scales and corrode more than their nickel-base counterparts which form NiO scales.

  7. Development of wear-resistant coatings for cobalt-base alloys

    International Nuclear Information System (INIS)

    Cockeram, B.V.

    1999-01-01

    The level of nuclear plant radiation exposure due to activated cobalt wear debris could potentially be reduced by covering the cobalt-base materials with a wear resistant coating. Laboratory pin-on-disc and rolling contact wear tests were used to evaluate the wear performance of several coatings. Based on the results of these tests, multilayer Cr-nitride coatings and ion nitriding are the most promising approaches

  8. Nickel, cobalt, and their alloys

    CERN Document Server

    2000-01-01

    This book is a comprehensive guide to the compositions, properties, processing, performance, and applications of nickel, cobalt, and their alloys. It includes all of the essential information contained in the ASM Handbook series, as well as new or updated coverage in many areas in the nickel, cobalt, and related industries.

  9. Derivative spectrophotometry of cobalt alloys

    International Nuclear Information System (INIS)

    Spitsyn, P.K.

    1985-01-01

    The method of derivative spectrophotometry is briefly described, and derivative absorption spectra are presented for samarium, cobalt, and commercial Sm-Co alloys. It is shown that the use of derivative spectrophotometry not only improves the accuracy and selectivity of element determinations but also simplifies the analysis of alloys. Results of a statistical evaluation of the metrological characteristics of the analytical procedure described here are presented. 8 references

  10. AN ELECTROPLATING METHOD OF FORMING PLATINGS OF NICKEL, COBALT, NICKEL ALLOYS OR COBALT ALLOYS

    DEFF Research Database (Denmark)

    1997-01-01

    An electroplating method of forming platings of nickel, cobalt, nickel alloys or cobalt alloys with reduced stresses in an electrodepositing bath of the type: Watt's bath, chloride bath or a combination thereof, by employing pulse plating with periodic reverse pulse and a sulfonated naphthalene...... additive. This method makes it possible to deposit nickel, cobalt, nickel or cobalt platings without internal stresses....

  11. Osseointegration of cobalt-chrome alloy implants.

    Science.gov (United States)

    Mavrogenis, Andreas F; Papagelopoulos, Panayiotis J; Babis, George C

    2011-01-01

    Osseointegration or osteointegration refers to a direct bone-to-metal interface without interposition of non-bone tissue. The long-term clinical success of bone implants is critically related to wide bone-to-implant direct contact. However, only poor bone formation or even host bone resorption have been shown where bone is in tight contact with the implant surface. It has been suggested that an appropriate space between implant and host bone may be useful for early peri-implant bone formation. Additionally, osseointegration depends on the topographical and chemical characteristics of the implant surface. Cobalt-chrome (Co-Cr) is a metal alloy of cobalt and chromium. Because of its high strength, temperature endurance and wear resistance, it is commonly used in dental and orthopedic implants. In orthopedic implants it is usually composed of cobalt with chromium, molybdenum, and traces of other elements. Co-Cr alloys are especially useful where high stiffness or a highly polished and extremely wear-resistant material is required. This article reviews the Co-Cr alloy orthopedic implants in terms of their properties, porous coating, osseointegration, outcome, and failure.

  12. Effect of Cobalt on Microstructure and Wear Resistance of Ni-Based Alloy Coating Fabricated by Laser Cladding

    Directory of Open Access Journals (Sweden)

    Kaiming Wang

    2017-12-01

    Full Text Available Ni-based alloy powders with different contents of cobalt (Co have been deposited on a 42CrMo steel substrate surface using a fiber laser. The effects of Co content on the microstructure, composition, hardness, and wear properties of the claddings were studied by scanning electron microscopy (SEM, an electron probe microanalyzer (EPMA, X-ray diffraction (XRD, a hardness tester, and a wear tester. The results show that the phases in the cladding layers are mainly γ, M7(C, B3, M23(C, B6, and M2B. With the increase in Co content, the amounts of M7(C, B3, M23(C, B6, and M2B gradually decrease, and the width of the eutectic structure in the cladding layer also gradually decreases. The microhardness decreases but the wear resistance of the cladding layer gradually improves with the increase of Co content. The wear resistance of the NiCo30 cladding layer is 3.6 times that of the NiCo00 cladding layer. With the increase of Co content, the wear mechanism of the cladding layer is changed from abrasive wear to adhesive wear.

  13. A comparison of corrosion resistance of cobalt-chromium-molybdenum metal ceramic alloy fabricated with selective laser melting and traditional processing.

    Science.gov (United States)

    Zeng, Li; Xiang, Nan; Wei, Bin

    2014-11-01

    A cobalt-chromium-molybdenum alloy fabricated by selective laser melting is a promising material; however, there are concerns about the change in its corrosion behavior. The purpose of this study was to evaluate the changes in corrosion behavior of a cobalt-chromium-molybdenum alloy fabricated by the selective laser melting technique before and after ceramic firing, with traditional processing of cobalt-chromium-molybdenum alloy serving as a control. Two groups of specimens were designated as group selective laser melting and group traditional. For each group, 20 specimens with a cylindrical shape were prepared and divided into 4 cells: selective laser melting as-cast, selective laser melting fired in pH 5.0 and 2.5, traditional as-cast, and traditional fired in pH 5.0 and 2.5. Specimens were prepared with a selective laser melting system for a selective laser melting alloy and the conventional lost wax technique for traditional cast alloy. After all specimen surfaces had been wet ground with silicon carbide paper (1200 grit), each group of 10 specimens was put through a series of ceramic firing cycles. Microstructure, Vickers microhardness, surface composition, oxide film thickness, and corrosion behavior were examined for specimens before and after ceramic firing. Three-way ANOVA was used to evaluate the effect of porcelain firing and pH values on the corrosion behavior of the 2 alloys (α=.05). Student t tests were used to compare the Vickers hardness. Although porcelain firing changed the microstructure, microhardness, and x-ray photoelectron spectroscopy results, it showed no significant influence on the corrosion behavior of the selective laser melting alloy and traditional cast alloy (P>.05). No statistically significant influence was found on the corrosion behavior of the 2 alloys in different pH value solutions (P>.05). The porcelain firing process had no significant influence on the corrosion resistance results of the 2 alloys. Compared with traditional

  14. Creep-resistant, cobalt-free alloys for high temperature, liquid-salt heat exchanger systems

    Energy Technology Data Exchange (ETDEWEB)

    Holcomb, David E; Muralidharan, Govindarajan; Wilson, Dane F.

    2016-09-06

    An essentially Fe- and Co-free alloy is composed essentially of, in terms of weight percent: 6.0 to 7.5 Cr, 0 to 0.15 Al, 0.5 to 0.85 Mn, 11 to 19.5 Mo, 0.03 to 4.5 Ta, 0.01 to 9 W, 0.03 to 0.08 C, 0 to 1 Re, 0 to 1 Ru, 0 to 0.001 B, 0.0005 to 0.005 N, balance Ni, the alloy being characterized by, at 850.degree. C., a yield strength of at least 25 Ksi, a tensile strength of at least 38 Ksi, a creep rupture life at 12 Ksi of at least 25 hours, and a corrosion rate, expressed in weight loss [g/(cm.sup.2 sec)]10.sup.-11 during a 1000 hour immersion in liquid FLiNaK at 850.degree. C., in the range of 3 to 10.

  15. Hot corrosion of low cobalt alloys

    Science.gov (United States)

    Stearns, C. A.

    1982-01-01

    The hot corrosion attack susceptibility of various alloys as a function of strategic materials content are investigated. Preliminary results were obtained for two commercial alloys, UDIMET 700 and Mar-M 247, that were modified by varying the cobalt content. For both alloys the cobalt content was reduced in steps to zero. Nickel content was increased accordingly to make up for the reduced cobalt but all other constituents were held constant. Wedge bar test samples were produced by casting. The hot corrosion test consisted of cyclically exposing samples to the high velocity flow of combustion products from an air-fuel burner fueled with jet A-1 and seeded with a sodium chloride aqueous solution. The flow velocity was Mach 0.5 and the sodium level was maintained at 0.5 ppm in terms of fuel plus air. The test cycle consisted of holding the test samples at 900 C for 1 hour followed by 3 minutes in which the sample could cool to room temperature in an ambient temperature air stream.

  16. Cobalt, nickel and chromium release from dental tools and alloys.

    Science.gov (United States)

    Kettelarij, Jolinde A B; Lidén, Carola; Axén, Emmy; Julander, Anneli

    2014-01-01

    Cobalt-chromium alloys are used as casting alloys by dental technicians when producing dental prostheses and implants. Skin exposure and metal release from alloys and tools used by the dental technicians have not been studied previously. To study the release of cobalt, nickel and chromium from alloys and tools that come into contact with the skin of dental technicians. Cobalt and nickel release from tools and alloys was tested with the cobalt spot test and the dimethylglyoxime test for nickel. Also, the release of cobalt, nickel and chromium in artificial sweat (EN1811) at different time-points was assessed. Analysis was performed with inductively coupled plasma-mass spectrometry. Sixty-one tools were spot tested; 20% released nickel and 23% released cobalt. Twenty-one tools and five dental alloys were immersed in artificial sweat. All tools released cobalt, nickel and chromium. The ranges were 0.0047-820, 0.0051-10 and 0.010-160 µg/cm(2) /week for cobalt, nickel and chromium, respectively. All dental alloys released cobalt in artificial sweat, with a range of 0.0010-17 µg/cm(2) /week, and they also released nickel and chromium at low concentrations. Sensitizing metals are released from tools and alloys used by dental technicians. This may cause contact allergy and hand eczema. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  17. Cobalt-containing alloys and their ability to release cobalt and cause dermatitis.

    Science.gov (United States)

    Julander, Anneli; Hindsén, Monica; Skare, Lizbet; Lidén, Carola

    2009-03-01

    Cobalt, nickel, and chromium are important skin sensitizers. However, knowledge about cobalt exposure and causes of cobalt sensitization is limited. To study release of cobalt, nickel, and chromium from some cobalt-containing hard metal alloys and to test reactivity to the materials in cobalt-sensitized patients. Discs suitable for patch testing were made of some hard metal alloys. Cobalt, nickel, and chromium release from the materials was determined by immersion in artificial sweat (2 min, 1 hr, 1 day, and 1 week). Patch test reactivity to the discs and to serial dilutions of cobalt and nickel was assessed in previously patch-tested dermatitis patients (19 cobalt positive and 18 cobalt-negative controls). All discs released cobalt, nickel, and chromium. Some discs released large amounts of cobalt (highest concentration: 290 microg/cm(2)/week). Seven discs elicited three or more positive test reactions. The concentration of released cobalt was high enough to elicit allergic contact dermatitis in cobalt-sensitized patients. As the materials in the discs are used in wear parts of hard metal tools, individuals with contact allergy to cobalt may develop hand eczema when handling such materials.

  18. Cobalt

    Science.gov (United States)

    Slack, John F.; Kimball, Bryn E.; Shedd, Kim B.; Schulz, Klaus J.; DeYoung,, John H.; Seal, Robert R.; Bradley, Dwight C.

    2017-12-19

    Cobalt is a silvery gray metal that has diverse uses based on certain key properties, including ferromagnetism, hardness and wear-resistance when alloyed with other metals, low thermal and electrical conductivity, high melting point, multiple valences, and production of intense blue colors when combined with silica. Cobalt is used mostly in cathodes in rechargeable batteries and in superalloys for turbine engines in jet aircraft. Annual global cobalt consumption was approximately 75,000 metric tons in 2011; China, Japan, and the United States (in order of consumption amount) were the top three cobalt-consuming countries. In 2011, approximately 109,000 metric tons of recoverable cobalt was produced in ores, concentrates, and intermediate products from cobalt, copper, nickel, platinum-group-element (PGE), and zinc operations. The Democratic Republic of the Congo (Congo [Kinshasa]) was the principal source of mined cobalt globally (55 percent). The United States produced a negligible amount of byproduct cobalt as an intermediate product from a PGE mining and refining operation in southeastern Montana; no U.S. production was from mines in which cobalt was the principal commodity. China was the leading refiner of cobalt, and much of its production came from cobalt ores, concentrates, and partially refined materials imported from Congo (Kinshasa).The mineralogy of cobalt deposits is diverse and includes both primary (hypogene) and secondary (supergene) phases. Principal terrestrial (land-based) deposit types, which represent most of world’s cobalt mine production, include primary magmatic Ni-Cu(-Co-PGE) sulfides, primary and secondary stratiform sediment-hosted Cu-Co sulfides and oxides, and secondary Ni-Co laterites. Seven additional terrestrial deposit types are described in this chapter. The total terrestrial cobalt resource (reserves plus other resources) plus past production, where available, is calculated to be 25.5 million metric tons. Additional resources of

  19. Microstructure And Functional Properties Of Prosthetic Cobalt Alloys CoCrW

    Directory of Open Access Journals (Sweden)

    Nadolski M.

    2015-09-01

    Full Text Available The material subject to investigation was two commercial alloys of cobalt CoCrW (No. 27 and 28 used in prosthodontics. The scope of research included performing an analysis of microstructure and functional properties (microhardness, wear resistance and corrosion resistance, as well as dilatometric tests. The examined alloys were characterized by diverse properties, which was considerably influenced by the morphology of precipitates in these materials. Alloy No. 27 has a higher corrosion resistance, whereas alloy No. 28 shows higher microhardness, better wear resistance and higher coefficient of linear expansion. Lower value of the expansion coefficient indicates less probability of initiation of a crack in the facing ceramic material.

  20. Synthesis of cobalt alloy through smelting method and its characterization as prosthesis bone implant

    Energy Technology Data Exchange (ETDEWEB)

    Aminatun,, E-mail: ami-sofijan@yahoo.co.id; Putri, N.S Efinda, E-mail: ami-sofijan@yahoo.co.id; Indriani, Arista, E-mail: ami-sofijan@yahoo.co.id; Himawati, Umi, E-mail: ami-sofijan@yahoo.co.id; Hikmawati, Dyah, E-mail: ami-sofijan@yahoo.co.id; Suhariningsih, E-mail: ami-sofijan@yahoo.co.id [Department of physics, Faculty of Science and Technology, Airlangga University (Indonesia)

    2014-09-25

    Cobalt-based alloys are widely used as total hip and knee replacements because of their excellent properties, such as corrosion resistance, fatigue strength and biocompatibility. In this work, cobalt alloys with variation of Cr (28.5; 30; 31.5; 33, and 34.5% wt) have been synthesized by smelting method began with the process of compaction, followed by smelting process using Tri Arc Melting Furnace at 200A. Continued by homogenization process at recrystallization temperature (1250° C) for 3 hours to allow the atoms diffuses and transform into γ phase. The next process is rolling process which is accompanied by heating at 1200° C for ± 15 minutes and followed by quenching. This process is repeated until the obtained thickness of ± 1 mm. The evaluated material properties included microstructure, surface morphology, and hardness value. It was shown that microstructure of cobalt alloys with variation of Cr is dominant by γ phase, thus making the entire cobalt alloys have high hardness. It was also shown from the surface morphology of entire cobalt alloys sample indicated the whole process of synthesis that had good solubility were at flat surface area. Hardness value test showed all of cobalt alloys sample had high hardness, just variation of 33% Cr be in the range of ASTMF75, it were 345,24 VHN which is potential to be applied as an implant prosthesis.

  1. [Effect of fluoride concentration on the corrosion behavior of cobalt-chromium alloy fabricated by two different technology processes].

    Science.gov (United States)

    Qiuxia, Yang; Ying, Yang; Han, Xu; Di, Wu; Ke, Guo

    2016-02-01

    This study aims to determine the effect of fluoride concentration on the corrosion behavior of cobalt-chromium alloy fabricated by two different technology processes in a simulated oral environment. A total of 15 specimens were employed with selective laser melting (SLM) and another 15 for traditional casting (Cast) in cobalt-chromium alloy powders and blocks with the same material composition. The corrosion behavior of the specimens was studied by potentiodynamic polarization test under different oral environments with varying solubilities of fluorine (0, 0.05%, and 0.20% for each) in acid artificial saliva (pH = 5.0). The specimens were soaked in fluorine for 24 h, and the surface microstructure was observed under a field emission scanning electron microscope after immersing the specimens in the test solution at constant temperature. The corrosion potential (Ecorr) value of the cobalt-chromium alloy cast decreased with increasing fluoride concentration in acidic artificial saliva. The Ecorr, Icorr, and Rp values of the cobalt-chromium alloy fabricated by two different technology processes changed significantly when the fluoride concentration was 0.20% (P technology processes exhibited a statistically significant difference. The Icorr value of the cobalt-chromium alloy cast was higher than that in the SLM group cobalt-chromium alloy when the fluoride concentration was 0.20% (P technology processes. The corrosion resistance of the cobalt-chromium alloy cast was worse than that of the SLM group cobalt-chromium alloy when the fluoride concentration was 0.20%.

  2. Advanced alloy design technique: High temperature cobalt base superalloy

    Science.gov (United States)

    Dreshfield, R. L.; Freche, J. C.; Sandrock, G. D.

    1972-01-01

    Advanced alloy design technique was developed for treating alloys that will have extended life in service at high temperature and intermediate temperatures. Process stabilizes microstructure of the alloy by designing it so that compound identified with embrittlement is eliminated or minimized. Design process is being used to develop both nickel and cobalt-base superalloys.

  3. Corrosion resistance of titanium alloys for dentistry

    International Nuclear Information System (INIS)

    Laskawiec, J.; Michalik, R.

    2001-01-01

    Titanium and its alloys belong to biomaterials which the application scope in medicine increases. Some properties of the alloys, such as high mechanical strength, low density, low Young's modulus, high corrosion resistance and good biotolerance decide about it. The main areas of the application of titanium and its alloys are: orthopedics and traumatology, cardiosurgery, faciomaxillary surgery and dentistry. The results of investigations concerning the corrosion resistance of the technical titanium and Ti6Al14V alloy and comparatively a cobalt alloy of the Vitallium type in the artificial saliva is presented in the work. Significantly better corrosion resistance of titanium and the Ti6Al14V than the Co-Cr-Mo alloy was found. (author)

  4. Pulse reversal plating of nickel-cobalt alloys

    DEFF Research Database (Denmark)

    Tang, Peter Torben; Jaskula, M.; Kubiczek, M.

    2009-01-01

    extreme demands, in terms of tool accuracy, process temperature and tool wear, are requested. In order to meet these demands, electroforming of hard nickel alloys is an obvious way forward. This paper presents several electrolytes from which it is possible to deposit nickel-cobalt alloys with high...

  5. Cobalt alloy ion sources for focused ion beam implantation

    Energy Technology Data Exchange (ETDEWEB)

    Muehle, R.; Doebeli, M. [Paul Scherrer Inst. (PSI), Villigen (Switzerland); Zimmermann, P. [Eidgenoessische Technische Hochschule, Zurich (Switzerland)

    1997-09-01

    Cobalt alloy ion sources have been developed for silicide formation by focused ion beam implantation. Four eutectic alloys AuCo, CoGe, CoY and AuCoGe were produced by electron beam welding. The AuCo liquid alloy ion source was investigated in detail. We have measured the emission current stability, the current-voltage characteristics, and the mass spectrum as a function of the mission current. (author) 1 fig., 2 refs.

  6. Metallic ion release from biocompatible cobalt-based alloy

    Directory of Open Access Journals (Sweden)

    Dimić Ivana D.

    2014-01-01

    Full Text Available Metallic biomaterials, which are mainly used for the damaged hard tissue replacements, are materials with high strength, excellent toughness and good wear resistance. The disadvantages of metals as implant materials are their susceptibility to corrosion, the elastic modulus mismatch between metals and human hard tissues, relatively high density and metallic ion release which can cause serious health problems. The aim of this study was to examine metallic ion release from Co-Cr-Mo alloy in artificial saliva. In that purpose, alloy samples were immersed into artificial saliva with different pH values (4.0, 5.5 and 7.5. After a certain immersion period (1, 3 and 6 weeks the concentrations of released ions were determined using Inductively Coupled Plasma - Mass Spectrophotometer (ICP-MS. The research findings were used in order to define the dependence between the concentration of released metallic ions, artificial saliva pH values and immersion time. The determined released metallic ions concentrations were compared with literature data in order to describe and better understand the phenomenon of metallic ion release from the biocompatible cobalt-based alloy. [Projekat Ministarstva nauke Republike Srbije, br. III 46010 i br. ON 174004

  7. Electrical Resistance Alloys and Low-Expansion Alloys

    DEFF Research Database (Denmark)

    Kjer, Torben

    1996-01-01

    The article gives an overview of electrical resistance alloys and alloys with low thermal expansion. The electrical resistance alloys comprise resistance alloys, heating alloys and thermostat alloys. The low expansion alloys comprise alloys with very low expansion coefficients, alloys with very low...

  8. Assessment of wrought ASTM F1058 cobalt alloy properties for permanent surgical implants.

    Science.gov (United States)

    Clerc, C O; Jedwab, M R; Mayer, D W; Thompson, P J; Stinson, J S

    1997-01-01

    The behavior of the ASTM F1058 wrought cobalt-chromium-nickel-molybdenum-iron alloy (commonly referred to as Elgiloy or Phynox) is evaluated in terms of mechanical properties, magnetic resonance imaging, corrosion resistance, and biocompatibility. The data found in the literature, the experimental corrosion and biocompatibility results presented in this article, and its long track record as an implant material demonstrate that the cobalt superalloy is an appropriate material for permanent surgical implants that require high yield strength and fatigue resistance combined with high elastic modulus, and that it can be safely imaged with magnetic resonance.

  9. Nanocrystalline Iron-Cobalt Alloys for High Saturation Indutance

    Science.gov (United States)

    2016-02-24

    AFRL-AFOSR-VA-TR-2016-0263 Nanocrystalline Iron- Cobalt Alloys for High saturation Indutance Conrad Williams MORGAN STATE UNIVERSITY (INC) 1700 E...YYYY) 28-02-2016 2. REPORT TYPE Final 3. DATES COVERED (From - To) 01 March 2013 -28 February 2016 4. TITLE AND SUBTITLE Nanocrystalline Iron- Cobalt ...driving the research at Morgan State University is “Can one achieve high magnetization (B > 1.7 T) at low fields (H < 1 mT) in iron- cobalt

  10. Improvement of sulfide corrosion resistance of nickel heat resisting alloys by means alloying

    International Nuclear Information System (INIS)

    Oryshkin, I.V.

    1999-01-01

    Paper describes the effect of the alloying elements (chromium, aluminium, titanium, molybdenum, tungsten, niobium, cobalt) on sulfide corrosion (SC) resistance of nickel base heat-resisting alloys during 30 h in 75% Na 2 SO 4 +25% NaCl molten sat under 900 deg C temperature. The obtained patterns are compared with the effect of the mentioned metals on the long-term strength. SC high resistance and the adequate level of heat resistance are ensured by a certain doping of a nickel base [ru

  11. The development of cobalt-base alloy ball bearing

    International Nuclear Information System (INIS)

    Yu Xinshui; Chen Jianting; Wang Zaishu; Wang Ximei; Huang Chongming.

    1986-01-01

    The main technologies and experiences in developing a Cobalt-base alloy ball bearing are described. In the hardfacing of bearing races, a lower-hardness alloy of type St-6 is used rather than an alloy with hardness similar to that of the ball and finally the hardness of race is increased to match that of the ball by heat treatment. This improvement has certain advantages. The experience of whole developing technology indicates that strict control of the technology in the bearing-race hardfacing is the key problem in the quality assurance of bearings

  12. Carburizing titanium and cobalt alloys in propane with simultaneous formation of a carbon coating

    Science.gov (United States)

    Nikonorova, I. V.; Gyulikhandanov, E. L.

    1998-02-01

    Deposition of a carbon coating onto structural materials used in medicine for artificial heart valves, stomatological structures, blood filters and other equipment improves their biological compatibility, surface hardness, and wear resistance. The present paper concerns a complex study of the possibility of preparing medical structures from titanium VT1-0 and cobalt 40KKhNM alloys by carburizing them with simultaneous deposition of a carbon coating.

  13. Tough and corrosion resistant austenitic alloy

    International Nuclear Information System (INIS)

    Johnson, T.E.

    1977-01-01

    The invention concerns austenitic alloys of high corrosion resistance, which can be deformed hot and tempered, so that they can be forged, rolled, and drawn into tubes and other shapes. The alloys have a basis of nickel, chromium and iron. The silicon content is between 2 and 4% by weight, and the molybdenum content is between 0 and 2% by weight. The alloys can be hardened by ageing and contain up to 0.1% by weight of boron. The other alloying materials are 1 to 3.5% by weight of manganese, 4 to 7.5% by weight of cobalt, 2.5 to 8% by weight of copper and 0.05 to 0.25% by weight of carbon. (IHOE) [de

  14. Sulfidation behavior of rhenium and cobalt-rhenium alloys

    International Nuclear Information System (INIS)

    Shiring, R.; Douglass, D.L.

    1999-01-01

    The sulfidation behavior of Re and three Co-Re alloys, 15, 30, and 45 w/o, was studied over the temperature range 700--800 C at sulfur pressures of 10 -4 and 10 -2 atm. The kinetics of sulfidation followed the parabolic rate law and the activation energies for all alloys were similar to that of pure cobalt. A positive rate dependency on sulfur pressure was observed and Pt markers were located at the metal-scale interface, both observations clearly suggesting that outward cation diffusion through a P-type sulfide scale occurred. Two dominant sulfides, Co 9 S 8 and ReS 2 , formed. Weight gains decreased for a given set of conditions with increasing rhenium content. An order of magnitude decrease in the sulfidation rate occurred as the rhenium content increased from 15 to 45 w/o. Preferential sulfidation of cobalt initially occurred, causing a rhenium-enriched zone to form in the substrate beneath the cobalt-sulfide scale. The initial sulfide to form was Co 3 S 4 , but, subsequently, Co 9 S 8 became the dominant sulfide, forming beneath the outer Co 3 S 4 layer. ReS 2 formed at lower cobalt levels. Pure Re was also studied, the sulfidation rate being about 10 4 times slower than that of cobalt. The decreasing rate of sulfidation with increasing Re content is attributed primarily to slower cobalt diffusion outward through the Re-enriched substrate, a phenomenon similar to that observed by C. Wagner for the oxidation of Ni-Pt alloys

  15. Design and characterization of a novel nickel-free cobalt-base alloy for intravascular stents.

    Science.gov (United States)

    Wang, Qiang; Ren, Yibin; Babar Shahzad, M; Zhang, Wei; Pan, Xumeng; Zhang, Song; Zhang, Dan

    2017-08-01

    Co-Cr-W-Ni alloy (L605) with high tensile strength is used in coronary stents. The thickness of individual strut of the stent is reduced which can decrease the stent restenosis rate. However, about 10% Ni element content in L605 is found to cause allergic reactions and pulmonary embolism, similar to the traditional 316L stainless steel. In this study, a novel nickel-free cobalt-base alloy Co-20Cr-12Fe-18Mn-2Mo-4W-N (wt%) was designed and fabricated in order to efficiently avoid the potential hazards of Ni element. Fe and Mn, essential elements of human body, were added in the alloy to substitute part of Co element. In comparison to L605 alloy, the tensile strength of the new alloy was higher than 1000MPa while elongation was above 55%. The pitting potential of the new alloy was measured close to 1000mV, also higher than that of L605 alloy. CCK-8 test indicated that the cytotoxicity of the new alloy is grade 1, reflecting that Co-20Cr-12Fe-18Mn-2Mo-4W-N alloy has no cytotoxic effects. There was no significant difference in the apoptosis rates between Co-20Cr-12Fe-18Mn-2Mo-4W-N and L605 alloy. The newly developed cobalt-base alloy showed excellent mechanical, corrosion resistance and biological properties, which could make it a desirable material for future clinical investigations. Copyright © 2017 Elsevier B.V. All rights reserved.

  16. Studies on the Codeposition of SiC Nanopowder with Nickel, Cobalt, and Co-Ni Alloys

    Directory of Open Access Journals (Sweden)

    Ewa Rudnik

    2014-01-01

    Full Text Available Electrodeposition of SiC nanopowder (approximately 120 nm with nickel, cobalt, and Co-Ni alloy matrix was studied. It was found that particles suspended in the bath affect slightly the reduction of metallic ions. Incorporation of the ceramic particles was governed mainly by the morphology of the matrix surface, while no strict correlation between the amount of cobalt ions adsorbed on the powder and the SiC content in the composites was found. Microhardness of nickel deposits was 585±5 HV, while for cobalt-rich coatings (84–95 wt.% Co the values were in the range of 260–290 HV, independently of the SiC content in the coatings. Fine-grained nickel deposits were characterized by good corrosion resistance, while cobalt and Co-Ni alloys showed high corrosion current densities.

  17. Testing of cobalt-free alloys for valve applications using a special test loop

    International Nuclear Information System (INIS)

    Benhamou, C.

    1992-01-01

    Considering that use of cobalt alloys should be avoided as far as possible in PWR components, a programme aimed at establishing the performance of cobalt-free alloys has been performed for valve applications, where cobalt alloys are mainly used. Referring to past work, two types of cobalt-free alloys were selected: Ni-Cr-B-Si and Ni-Cr-Fe alloys. Cobalt-free valves' behaviour has been evaluated comparatively with cobalt valves by implementation of a programme in a special PWR test loop. At the issue of the loop test programme, which included endurance, thermal shock and erosion tests, cobalt-free alloys candidate to replace cobalt alloys are proposed in relation with valve type (globe valve and swing check valve). The following was established: (i) Colmonoy 4-26 (Ni-Cr-B-Si alloy) and Cenium Z20 (Ni-Cr-Fe alloy) deposited by plasma arc process were found suitable for use in 3inch swing check valves; (ii) for integral parts acting as guide rings, Nitronic 60 and Cesium Z20/698 were tested successfully; (iii) for small-bore components such as 2inch globe valves, no solution can yet be proposed; introduction of cobalt-free alloys is dependent on the development of automatic advanced arc surfacing techniques applied to small-bore components

  18. Alloys having improved resistance to hydrogen embrittlement

    International Nuclear Information System (INIS)

    Kane, R.D.; Greer, J.B.; Jacobs, D.F.; Berkowitz, B.J.

    1983-01-01

    The invention involves a process of improving the hydrogen embrittlement resistance of a cold-worked high yield strength nickel/cobalt base alloy containing chromium, and molybdenum and/or tungsten and having individual elemental impurity concentrations as measured by Auger spectroscopy at the crystallographic boundaries of up to about 1 Atomic percent. These elemental impurities are capable of becoming active and mobile at a temperature less than the recrystallization temperature of the alloy. The process involves heat treating the alloy at a temperature above 1300 degrees F but below the temperature of recrystallization for a time of from 1/4 to 100 hours. This is sufficient to effect a reduction in the level of the elemental impurities at the crystallographic boundaries to the range of less than 0.5 Atomic percent without causing an appreciable decrease in yield strength

  19. Mechanical evaluation of cerebral aneurysm clip scissoring phenomenon: comparison of titanium alloy and cobalt alloy.

    Science.gov (United States)

    Tsutsumi, Keiji; Horiuchi, Tetsuyoshi; Hongo, Kazuhiro

    2017-09-13

    Cerebral aneurysm clip blades crossing during surgery is well known as scissoring. Scissoring might cause rupture of the aneurysm due to laceration of its neck. Although aneurysm clip scissoring is well known, there have been few reports describing the details of this phenomenon. Quasi-scissoring phenomenon was introduced mechanically by rotating the clip head attached to a silicone sheet. The anti-scissoring torque during the twist of the blades was measured by changing the depth and the opening width. The closing force was also evaluated. Sugita straight clips of titanium alloy and cobalt alloy were used in the present study. In both materials, the anti-scissoring torque and the closing force were bigger 3 mm in thickness than 1 mm. The initial closing forces and the anti-scissoring torque values at each rotation angles were increased in proportion to depth. Closing forces of titanium alloy clip were slightly higher than those of cobalt alloy clip. By contrast, anti-scissoring torque values of cobalt alloy clip were bigger than those of titanium alloy clip in all conditions. In condition of 3 mm in thickness and 3 mm in depth, anti-scissoring torque vales of titanium alloy clip decreased suddenly when an angle surpassed 70 degrees. Aneurysm clip scissoring phenomenon tends to occur when clipping the aneurysm neck only with blade tips. Based on the results of this experiment, titanium alloy clip is more prone to scissoring than cobalt alloy clip under the condition that the wide blade separation distance and the shallow blade length.

  20. Berkovich nanoindentation and deformation mechanisms in a hardmetal binder-like cobalt alloy

    OpenAIRE

    Roa Rovira, Joan Josep; Jiménez Piqué, Emilio; Tarragó Cifre, Jose María; Zivcec, Maria; Broeckmann, C.; Llanes Pitarch, Luis Miguel

    2014-01-01

    A cobalt-base solid solution is the most used binder for hardmetals (WC–Co cemented carbides) in a wide range of industrial applications. In the composite material such cobalt alloy is surrounded by hard carbides grains; thus, a direct evaluation of its intrinsic mechanical properties is not an easy task. In order to overcome this inconvenience, a model cobalt alloy with a composition similar to that exhibited by typical hardmetal binder (containing W and C in solid solution) was processed fo...

  1. Substitution of cobalt alloying in PWR primary circuit gate valves

    International Nuclear Information System (INIS)

    Cachon, L.; Sudreau, F.; Brunel, L.

    1995-01-01

    The object of this study is qualify cobalt-free alternative alloys for valve applications. This paper focus on tribological characterization of numerous coatings is done by using the first one, of a classical type. Then tests are performed with the second one which simulates solicitations supported by gate valves in primary circuit of PWR. 35% Ni-Cr - 65% Cr 3 C 2 coating, deposited by detonation gun technology, gives us hope to find a substitute of Stelite 6. (author). 5 refs., 16 figs., 2 tabs

  2. Analysis of thermoelectric properties of high-temperature complex alloys of nickel-base, iron-base and cobalt-base groups

    Science.gov (United States)

    Holanda, R.

    1984-01-01

    The thermoelectric properties alloys of the nickel-base, iron-base, and cobalt-base groups containing from 1% to 25% 106 chromium were compared and correlated with the following material characteristics: atomic percent of the principle alloy constituent; ratio of concentration of two constituents; alloy physical property (electrical resistivity); alloy phase structure (percent precipitate or percent hardener content); alloy electronic structure (electron concentration). For solid-solution-type alloys the most consistent correlation was obtained with electron concentration, for precipitation-hardenable alloys of the nickel-base superalloy group, the thermoelectric potential correlated with hardener content in the alloy structure. For solid-solution-type alloys, no problems were found with thermoelectric stability to 1000; for precipitation-hardenable alloys, thermoelectric stability was dependent on phase stability. The effects of the compositional range of alloy constituents on temperature measurement uncertainty are discussed.

  3. Mechanical properties of metal-ceramic systems from nickel-chromium and cobalt-chromium alloys

    Directory of Open Access Journals (Sweden)

    Mirković Nemanja

    2007-01-01

    Full Text Available Background/Aim. Metal-ceramic bond strength and alloys' elastic modulus clearly determine the potential of alloy application, because the ceramic integrity during mastication depends on these two characteristics. The aim of this study was to evaluate metal-ceramic bond strength and elastic modulus of cobalt-chromium alloys in making porcelainfused- to-metal restorations, regarding the application of the most frequent nickel-chromium alloy. Methods. The research was performed as an experimental study. Six metalceramic samples were made from nickel-chromium alloy (Wiron 99 and cobalt-chromium alloy (Wirobond C, according to the manufactures manuals and instructions from ISO 9693: 1996. Three-point bending test was performed up to the ceramic fracture. The fracture load was measured on an universal testing machine (Zwick, type 1464, with cross-head speed of 0,05mm/min. Results. The results of this study confirmed the significant differences between the metal-ceramic bond strength (p < 0.01 and elastic modulus (p < 0.001 of nickel-chromium and cobalt-chromium alloys, where cobalt-chromium alloys showed higher values for both tested parameters. Conclusion. Cobalt-chromium metal-ceramic alloys can successfully replace nickel-chromium alloys, especially for fabrication of long-span metal-ceramic bridges due to the great flexural strength.

  4. Castable hot corrosion resistant alloy

    Science.gov (United States)

    Barrett, Charles A. (Inventor); Holt, William H. (Inventor)

    1988-01-01

    Some 10 wt percent nickel is added to an Fe-base alloy which has a ferrite microstructure to improve the high temperature castability and crack resistance while about 0.2 wt percent zirconium is added for improved high temperatur cyclic oxidation and corrosion resistance. The basic material is a high temperature FeCrAl heater alloy, and the addition provides a material suitable for burner rig nozzles.

  5. The substitution of nickel for cobalt in hot isostatically pressed powder metallurgy UDIMET 700 alloys

    Science.gov (United States)

    Harf, F. H.

    1985-01-01

    Nickel was substituted in various proportions for cobalt in a series of five hot-isostatically-pressed powder metallurgy alloys based on the UDIMET 700 composition. These alloys were given 5-step heat treatments appropriate for use in turbine engine disks. The resultant microstructures displayed three distinct sizes of gamma-prime particles in a gamma matrix. The higher cobalt-content alloys contained larger amounts of the finest gamma-prime particles, and had the lowest gamma-gamma-prime lattice mismatch. While all alloys had approximately the same tensile properties at 25 and 650 gamma C, the rupture lives at 650 and 760 C peaked in the alloys with cobalt contents between 12.7 and 4.3 pct. Minimum creep rates increased as cobalt contents were lowered, suggesting their correlation with the gamma-prime particle size distribution and the gamma-gamma-prime mismatch. It was also found that, on overaging at temperatures higher than suitable for turbine disk use, the high cobalt-content alloys were prone to sigma phase formation.

  6. Synthesis and characterization of iron-cobalt (FeCo) alloy nanoparticles supported on carbon

    DEFF Research Database (Denmark)

    Koutsopoulos, Sotiris; Barfod, Rasmus; Eriksen, Kim Michael

    2017-01-01

    Iron-cobalt nanocrystaline bimetallic alloys supported on carbon microparticles were synthesized and characterized. The preparation methods involved the use of iron and cobalt chloride or acetate precursor salts in water and direct co-precipitation or wet impregnation techniques. The size...... of the alloy nanoparticles differed depending on the preparation method. When the wet impregnation technique of acetate precursor salts of Fe and Co were used for the synthesis, the size of FeCo alloy nanoparticles was approximately 13 nm. FeCo alloy nanoparticles were characterized by crystallography (XRD...... and mechanically stable for prolonged periods of time. AFM analysis showed that the FeCo nanoparticles were formed on the surface of the carrier. The results of this study suggest that using these easy and inexpensive synthetic methods iron-cobalt nanoparticles can be formed on carbon microparticles support...

  7. Alloying principles for magnesium base heat resisting alloys

    International Nuclear Information System (INIS)

    Drits, M.E.; Rokhlin, L.L.; Oreshkina, A.A.; Nikitina, N.I.

    1982-01-01

    Some binary systems of magnesium-base alloys in which solid solutions are formed, are considered for prospecting heat resistant alloys. It is shown that elements having essential solubility in solid magnesium strongly decreasing with temperature should be used for alloying maqnesium base alloys with high strength properties at increased temperatures. The strengthening phases in these alloys should comprise essential quantity of magnesium and be rather refractory

  8. Influence of Cobalt on the Properties of Load-Sensitive Magnesium Alloys

    Directory of Open Access Journals (Sweden)

    Kai Kerber

    2012-12-01

    Full Text Available In this study, magnesium is alloyed with varying amounts of the ferromagnetic alloying element cobalt in order to obtain lightweight load-sensitive materials with sensory properties which allow an online-monitoring of mechanical forces applied to components made from Mg-Co alloys. An optimized casting process with the use of extruded Mg-Co powder rods is utilized which enables the production of magnetic magnesium alloys with a reproducible Co concentration. The efficiency of the casting process is confirmed by SEM analyses. Microstructures and Co-rich precipitations of various Mg-Co alloys are investigated by means of EDS and XRD analyses. The Mg-Co alloys’ mechanical strengths are determined by tensile tests. Magnetic properties of the Mg-Co sensor alloys depending on the cobalt content and the acting mechanical load are measured utilizing the harmonic analysis of eddy-current signals. Within the scope of this work, the influence of the element cobalt on magnesium is investigated in detail and an optimal cobalt concentration is defined based on the performed examinations.

  9. Thermal cooling effects in the microstructure and properties of cast cobalt-base biomedical alloys

    Science.gov (United States)

    Vega Valer, Vladimir

    Joint replacement prosthesis is widely used in the biomedical field to provide a solution for dysfunctional human body joints. The demand for orthopedic knee and hip implants motivate scientists and manufacturers to develop novel materials or to increase the life of service and efficiency of current materials. Cobalt-base alloys have been investigated by various researchers for biomedical implantations. When these alloys contain Chromium, Molybdenum, and Carbon, they exhibit good tribological and mechanical properties, as well as excellent biocompatibility and corrosion resistance. In this study, the microstructure of cast Co-Cr-Mo-C alloy is purposely modified by inducing rapid solidification through fusion welding processes and solution annealing heat treatment (quenched in water at room temperature. In particular the effect of high cooling rates on the athermal phase transformation FCC(gamma)↔HCP(epsilon) on the alloy hardness and corrosion resistance is investigated. The Co-alloy microstructures were characterized using metallography and microscopy techniques. It was found that the as cast sample typically dendritic with dendritic grain sizes of approximately 150 microm and containing Cr-rich coarse carbide precipitates along the interdendritic boundaries. Solution annealing gives rise to a refined microstructure with grain size of 30 microm, common among Co-Cr-Mo alloys after heat treating. Alternatively, an ultrafine grain structure (between 2 and 10 microm) was developed in the fusion zone for specimens melted using Laser and TIG welding methods. When laser surface modification treatments were implemented, the developed solidification microstructure shifted from dendritic to a fine cellular morphology, with possible nanoscale carbide precipitates along the cellular boundaries. In turn, the solidified regions exhibited high hardness values (461.5HV), which exceeds by almost 110 points from the alloy in the as-cast condition. The amount of developed athermal

  10. Electrocatalytic properties of cobalt-molybdenum alloy precipitates in hydrogen evolution reaction

    International Nuclear Information System (INIS)

    Kuznetsov, V.V.; Kalinkina, A.A.; Pshenichkina, T.V.; Balabaev, V.V.

    2008-01-01

    Electrocatalytic activity of cobalt-molybdenum precipitates concerning hydrogen evolution in alkali solution has been studied. Electrode materials were prepared by electrochemical method in galvanostatic regime. It is demonstrated that hydrogen evolution rate in 1M NaOH at 293 K at the Co-Mo alloy is higher as compared with the pure cobalt precipitates prepared similarly. It is in accord with the increasing true area of the electrode surface, and, perhaps, with electronic structure of the prepared alloys. It is established that exchange current of the hydrogen reaction increases when molybdenum content rises in electrode precipitates in the interval 0-40 at.% [ru

  11. Tensile strength of laser welded cobalt-chromium alloy with and without an argon atmosphere.

    Science.gov (United States)

    Tartari, Anna; Clark, Robert K F; Juszczyk, Andrzej S; Radford, David R

    2010-06-01

    The tensile strength and depth of weld of two cobalt chromium alloys before and after laser welding with and without an argon gas atmosphere were investigated. Using two cobalt chromium alloys, rod shaped specimens (5 cm x 1.5 mm) were cast. Specimens were sand blasted, sectioned and welded with a pulsed Nd: YAG laser welding machine and tested in tension using an Instron universal testing machine. A statistically significant difference in tensile strength was observed between the two alloys. The tensile strength of specimens following laser welding was significantly less than the unwelded controls. Scanning electron microscopy showed that the micro-structure of the cast alloy was altered in the region of the weld. No statistically significant difference was found between specimens welded with or without an argon atmosphere.

  12. Influence of temperature, grain size and cobalt content on the hardness of WC-Co alloys

    CSIR Research Space (South Africa)

    Milman, YV

    1999-01-01

    Full Text Available , grain size and cobalt content on the hardness of WC?Co alloys Yu.V. Milman a, S. Luyckx b,c, IT Northrop d a Institute of Problems in Materials Science, Kiev, Ukraine b School of Process and Materials Engineering, University of the Witwatersrand...

  13. Incentives and opportunities for reducing the cobalt content in reactor core components

    International Nuclear Information System (INIS)

    Ocken, H.

    1985-01-01

    Cobalt in core components contributes to radiation field buildup on out-of-core surfaces. Core components containing cobalt-base alloys and cobalt as an impurity are identified. The use of cobalt-free wear-resistant alloys and construction materials with lower impurity levels of cobalt is disused. It is argued that such measures are cost effective. Lower radiation fields and disposal costs will offset higher raw material costs. Component performance will not be affected. (author)

  14. Construction of an apparatus for nuclear orientation measurements at low temperatures. Application to neodymium-cobalt alloy

    International Nuclear Information System (INIS)

    Mayer, E.

    1965-10-01

    We describe experiments along which has been studied the anisotropy of γ radiations emitted by oriented nuclei. We have used the great hyperfine fields acting on nuclei in ferromagnetic metals so as to produce alignment at low temperature. By irradiation we obtained a few cobalt 60 nuclei in our samples which were then cooled down to 0,01 K. The anisotropic rate of the 1,33 MeV γ radiation was measured in function of the sample temperature, using as thermometer the anisotropy of γ radiation emitted by cobalt 60 nuclei in a cobalt single crystal. Cobalt 60 was lined up in a cobalt nickel alloy (40% Ni). The hyperfine field at the cobalt was measured compared to the effective field in metallic cobalt: Heff(Co Ni)/Heff(Co metal) = 0.71 ± 0.12. These results are in good agreement with specific heat measurements made previously. Cobalt 60 has been polarised in a neodymium-cobalt alloy (NdCo 5 ). The field at the cobalt in NdCo 5 has been measured compared to the field in metallic cobalt and taking the non-saturation into account we found 165000 oersteds 5 ) [fr

  15. Producing Low-Oxygen Samarium/Cobalt Magnet Alloy

    Science.gov (United States)

    Das, Dilip K.; Kumar, Kaplesh; Frost, Robert T.; Chang, C. W.

    1987-01-01

    Experiments aimed at producing SmCo5 alloy with low oxygen contamination described in report. Two methods of alloying by melting without contact with crucible walls tested. Lowest oxygen contamination, 70 parts per million achieved by dc arc melting on water-cooled, tantalum-clad copper hearth in purified quiescent argon atmosphere. Report includes photographs of equipment, photomicrographs of alloy samples, detailed descriptions of procedures tried, and tables of oxygen contamination and intrinsic coercivities of samples produced.

  16. Cobalt-rich alloys electrodeposited on silicon; Filmes de ligas ricas em cobalto eletrodepositado sobre silicio

    Energy Technology Data Exchange (ETDEWEB)

    Spada, E.R.; Dotto, M.E.R.; Sartorelli, M.L. [Universidade Federal de Santa Catarina (UFSC), Florianopolis, SC (Brazil). Departamento de Fisica. Lab. de Sistemas Nanoestruturados; Paula, F.R. de, E-mail: depaula@dfq.feis.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Ilha Solteira, SP (Brazil). Departamento de Fisica e Quimica

    2014-07-01

    We report the electrodeposition (ED) of cobalt-rich alloy films on n-type Si (100) substrates in aqueous solution. A small amount of copper sulphate in the bath improved the quality of cobalt-rich films. The bath proved to be appropriate for the production of electrodeposited magnetic antidote structures prepared by nanosphere lithography technique. X-ray measurements indicate a mixture of hcp and fcc CoCu structures and strong texture in the (001) hcp and (111) fcc direction. Magnetic behavior was shown to be dependent on the thickness, which directly affects the domain wall pinning and the presence of superparamagnetism. (author)

  17. A comparison study of polymer/cobalt ferrite nano-composites synthesized by mechanical alloying route

    Directory of Open Access Journals (Sweden)

    Sedigheh Rashidi

    2015-12-01

    Full Text Available In this research, the effect of different biopolymers such as polyethylene glycol (PEG and polyvinylalcohol (PVA on synthesis and characterization of polymer/cobalt ferrite (CF nano-composites bymechanical alloying method has been systematically investigated. The structural, morphological andmagnetic properties changes during mechanical milling were investigated by X-ray diffraction (XRD,Fourier transform infrared spectroscopy (FTIR, transmission electron microscopy (TEM, fieldemission scanning electron microscopy (FESEM, and vibrating sample magnetometer techniques(VSM, respectively. The polymeric cobalt ferrite nano-composites were obtained by employing atwo-step procedure: the cobalt ferrite of 20 nm mean particle size was first synthesized by mechanicalalloying route and then was embedded in PEG or PVA biopolymer matrix by milling process. Theresults revealed that PEG melted due to the local temperature raise during milling. Despite thisphenomenon, cobalt ferrite nano-particles were entirely embedded in PEG matrix. It seems, PAV is anappropriate candidate for producing nano-composite samples due to its high melting point. InPVA/CF nano-composites, the mean crystallite size and milling induced strain decreased to 13 nm and0.48, respectively. Moreover, milling process resulted in well distribution of CF in PVA matrix eventhough the mean particle size of cobalt ferrite has not been significantly affecetd. FTIR resultconfirmed the attachment of PVA to the surface of nano-particles. Magnetic properties evaluationshowed that saturation magnetization and coercivity values decreased in nano-composite samplecomparing the pure cobalt ferrite.

  18. Structure and corrosion resistance of Co-Cr-Mo alloy used in Birmingham Hip Resurfacing system.

    Science.gov (United States)

    Dobruchowska, Ewa; Paziewska, Monika; Przybyl, Krzysztof; Reszka, Kazimierz

    2017-01-01

    The endoprostheses made of cobalt-chromium-molybdenum (Co-Cr-Mo) alloys belong to the group of the most popular metallic implants used for reconstruction of hip joints. For such biomaterials, the primary goal is a correct and long-term functioning in the aggressive environment of body fluids. Therefore, the purpose of this study was to examine both the morphology and the corrosion resistance of implants made of the cobalt alloy used in Birmingham Hip Resurfacing (BHR) system (Smith & Nephew). For comparative purposes, the electrochemical studies were done for the nitrided stainless steel - Orthinox. Observations of the microstructure of the material under investigation were performed by means of the optical metallographic microscope and the scanning electron microscope. Furthermore, Energy Dispersive X-ray Spectroscopy was used to analyse the chemical composition of the endoprosthesis. Characterisation and evaluation of electrochemical corrosion resistance of the selected alloys were performed by potentiodynamic polarisation tests. The structural studies confirmed that Co-Cr-Mo (BHR system) is characterised by a typical dendritic microstructure with carbide precipitates, mainly M23C6, within the interdendritic areas. The results of the polarisation measurements showed that the cobalt alloy investigated exhibits lower corrosion potential than Orthinox in the utilised environments (3% NaCl, simulated body fluid - Hank's Body Fluid). However, the high passivation ability of the Co-Cr-Mo alloy, as well as its resistance to the initiation and propagation of localised corrosion processes, indicate that this material is significantly more appropriate for long-term implants.

  19. Wrought cobalt- base superalloys

    Science.gov (United States)

    Klarstrom, D. L.

    1993-08-01

    Wrought cobalt-base superalloys are used extensively in gas turbine engines because of their excellent high-temperature creep and fatigue strengths and resistance to hot corrosion attack. In addition, the unique character of the oxide scales that form on some of the alloys provides outstanding resistance to high-temperature sliding wear. This article provides a review of the evolutionary development of wrought cobalt-base alloys in terms of alloy design and physical metallurgy. The topics include solid-so-lution strengthening, carbide precipitation characteristics, and attempts to introduce age hardening. The use of PHACOMP to enhance thermal stability characteristics and the incorporation of rare-earth ele-ments to improve oxidation resistance is also reviewed and discussed. The further development of cobalt-base superalloys has been severely hampered by past political events, which have accentuated the strategic vulnerability of cobalt as a base or as an alloying element. Consequently, alternative alloys have been developed that use little or no cobalt. One such alternative, Haynes® 230TMalloy, is discussed briefly.

  20. Thermodynamic Considerations of Contamination by Alloying Elements of Remelted End-of-Life Nickel- and Cobalt-Based Superalloys

    Science.gov (United States)

    Lu, Xin; Matsubae, Kazuyo; Nakajima, Kenichi; Nakamura, Shinichiro; Nagasaka, Tetsuya

    2016-06-01

    Cobalt and nickel are high-value commodity metals and are mostly used in the form of highly alloyed materials. The alloying elements used may cause contamination problems during recycling. To ensure maximum resource efficiency, an understanding of the removability of these alloying elements and the controllability of some of the primary alloying elements is essential with respect to the recycling of end-of-life (EoL) nickel- and cobalt-based superalloys by remelting. In this study, the distribution behaviors of approximately 30 elements that are usually present in EoL nickel- and cobalt-based superalloys in the solvent metal (nickel, cobalt, or nickel-cobalt alloy), oxide slag, and gas phases during the remelting were quantitatively evaluated using a thermodynamic approach. The results showed that most of the alloying elements can be removed either in the slag phase or into the gas phase. However, the removal of copper, tin, arsenic, and antimony by remelting is difficult, and they remain as tramp elements during the recycling. On the other hand, the distribution tendencies of iron, molybdenum, and tungsten can be controlled by changing the remelting conditions. To increase the resource efficiency of recycling, preventing contamination by the tramp elements and identifying the alloying compositions of EoL superalloys are significantly essential, which will require the development of efficient prior alloy-sorting systems and advanced separation technologies.

  1. Structure effect on wear resistance of alloys

    International Nuclear Information System (INIS)

    Stepina, A.I.; Sidorova, L.I.; Tolstenko, E.V.

    1982-01-01

    The dependence of wear resistance on hardness of steels with different microstructure is studied under conditions of gas-abrasion wear of surface layers. It is found out that at the same hardness the wear resistance of α-alloys is higher than that of γ-alloys in spite of considerable surface hardening of austenitic alloys. Fracture of surface in the process of abrasive wear occurs after achievement of definite values of microhardness and the width of a diffraction line for each structural class of alloys [ru

  2. [Comparison of the clinical effects of selective laser melting deposition basal crowns and cobalt chromium alloy base crowns].

    Science.gov (United States)

    Li, Jing-min; Wang, Wei-qian; Ma, Jing-yuan

    2014-06-01

    To evaluate the clinical effects of selective laser melting (SLM) deposition basal crowns and cobalt chromium alloy casting base crowns. One hundred and sixty eight patients treated with either SLM deposition basal crowns (110 teeth) or cobalt chromium alloy casting basal crowns (110 teeth) were followed-up for 1 month, 6 months, 12 months and 24 months. The revised standard of American Public Health Association was used to evaluate the clinical effect of restoration, including the color of porcelain crowns, gingival inflammation, gingival margin discoloration, and crack or fracture. Data analysis was conducted with SPSS 20 software package for Student's t test and Chi-square test. Six cases were lost to follow-up. The patients who were treated with SLM deposition basal crowns (104 teeth) and cobalt chromium alloy casting base crowns (101 teeth) completed the study. Patients were more satisfied with SLM deposition cobalt chromium alloy porcelain crowns. There was 1 prosthesis with poor marginal fit after 24 months of restoration in SLM crowns. There were 6 prostheses with edge coloring and 8 with poor marginal fit in cobalt chromium alloy casting base crowns, which was significantly different between the 2 groups(P<0.05). The SLM deposition copings results in smaller edge coloring and better marginal fit than those of cobalt-chrome copings. Patients are pleased with short-term clinical results.

  3. Calculated magnetization of iron-cobalt disordered alloys

    International Nuclear Information System (INIS)

    Victora, R.H.; Falicov, L.M.

    1984-01-01

    The spin polarization of the disordered Fe-Co alloy was calculated using a tight-binding scheme, with single-site, full-orbital interactions treated self-consistently. Disorder is introduced by the use of the virtual-crystal approximation. Excellent agreement with the experimental spin polarization is obtained and the unusual shape of the Fe-Co curve on the Slater-Pauling plot is explained. The magnetization of the Co-rich alloys essentially depends on the number of available d holes, while the magnetization of the Fe-rich alloys is influenced by a relatively weak electron-electron interaction. The intersection of the two effects occurs at approximately 30 at. % Co and produces a maximum

  4. Synthesis and characterization of palladium-cobalt alloy for new medical micro-devices

    Science.gov (United States)

    Kafrouni, Lina

    According to Canadian Cancer Statistics, it is estimated that 196,900 Canadians will develop cancer and 78,000 will die of cancer in 2015. Given that tumor cells are more sensitive to a temperature increase than healthy ones, this property can be used in vivo to destroy the cancerous cells by elevation of body temperature, otherwise known as hyperthermia. Magnetic hyperthermia is a promising technique for cancer treatment because of ease in targeting the cancerous cells using magnetic nanoparticles (MNPs) and hence having fewer side effects than chemotherapy and radiotherapy. Despite the use of magnetic hyperthermia to treat cancer for thousands of years, the challenge of only heating malignant cells remains daunting. Thus, oncologists often use the heat treatment in combination with radiotherapy or chemotherapy or both. The combined approach results in eliminating many cancer cells in addition to making the resistant cancer cells more vulnerable to other treatments. To use stand-alone magnetic hyperthermia therapy, difficulties in surface modification of magnetic particles for selective uptake by cancerous cells and stability as well as magnetic properties for high heating capacity (> 1000 W/g) must be overcome. The ultimate objective of this thesis is to synthesize an excellent candidate for a powerful magnetic hyperthermia. Due to rapid advances in nanotechnology, a synthesis method of nanoparticles (NPs) with the ability to rigorously control the structure and morphology, such as size, shape and crystallinity, is needed. Electrodeposition is a versatile method for the synthesis of metal NPs directly and selectively onto conductive substrates, simply by regulating applied current or voltage. Furthermore, the particles size and the shape are easily controllable. Besides, studies have shown that the electrodeposition technique is of great utility in the fabrication of nanocrystalline palladium-cobalt (PdCo) alloys. The primary goal of this project is to synthesize

  5. Cobalt reduction of NSSS valve hardfacings for ALARA

    International Nuclear Information System (INIS)

    Kim, Joo Hak; Lee, Sang Sub

    1994-07-01

    This report informs NSSS designer that replacement of materials is one of the major means of ALARA implementation, and describes that NSSS valves with high-cobalt hardfacing are significant contributors to post-shutdown radiation fields caused by activation of cobalt-59 to cobalt-60. Generic procedures for implementing cobalt reduction programs for valves are presented. Discussions are presented of the general and specific design requirements for valve hardfacing in nuclear service. The nuclear safety issues involved with changing valve hardfacing materials are discussed. The common methods used to deposit hardfacing materials are described together with an explanation of the wear measurements. Wear resistance, corrosion resistance, friction coefficient, and mechanical properties of candidate hardfacing alloys are given. World-wide nuclear utility experience with cobalt-free hardfacing alloys is described. The use of low-cobalt or cobalt-free alloys in other nuclear plant components is described. 17 figs., 38 tabs., 18 refs. (Author)

  6. Cobalt

    International Nuclear Information System (INIS)

    Stolyarova, I.A.; Bunakova, N.Yu.

    1983-01-01

    The neutron-activation method for determining cobalt in rocks, polymetallic and iron ores and rockforming minerals at 2x10 -6 -5x10 -3 % content is developed. Cobalt determination is based on the formation under the effect of thermal neutrons of nuclear reactor of the 60 Co radioactive isotope by the 59 Co (n, γ) 60 Co reaction with radiation energy of the most intensive line of 1333 keV. Cobalt can be determined by the scheme of the multicomponent analysis from the sample with other elements. Co is determined in the solution after separation of all determinable by the scheme elements. The 60 Co intensity is measured by the mUltichannel gamma-spectrometer with Ge(Li)-detector

  7. Characterization of fabricated cobalt-based alloy/nano bioactive glass composites

    International Nuclear Information System (INIS)

    Bafandeh, Mohammad Reza; Gharahkhani, Raziyeh; Fathi, Mohammad Hossein

    2016-01-01

    In this work, cobalt-based alloy/nano bioactive glass (NBG) composites with 10, 15 and 20 wt% NBG were prepared and their bioactivity after immersion in simulated body fluid (SBF) for 1 to 4 weeks was studied. Scanning electron microscopy images of two- step sintered composites revealed relatively dense microstructure. The results showed that density of composite samples decreased with increase in NBG amount. The microstructure analysis as well as energy dispersive X-ray analysis (EDX) revealed that small amount of calcium phosphate phases precipitates on the surface of composite samples after 1 week immersion in SBF. After 2 weeks immersion, considerable amounts of cauliflower-like shaped precipitations were seen on the surface of the composites. Based on EDX analysis, these precipitations were composed mainly from Ca, P and Si. The observed bands in the Fourier transform infrared spectroscopy of immersed composites samples for 4 weeks in SBF, were characteristic bands of hydroxyapatite. Therefore it is possible to form hydroxyapatite layer on the surface of composite samples during immersion in SBF. The results indicated that prepared composites unlike cobalt-based alloy are bioactive, promising their possibility for implant applications. - Highlights: • Co-based alloy/nano bioactive glass (NBG) composites with 10, 15 and 20 wt% NBG were prepared. • In order to study their bioactivity, composite samples were immersed in SBF solution for 1 to 4 weeks. • Immersion in SBF accompanied with precipitation of hydroxyapatite on surface of samples. • Prepared composite samples unlike cobalt-based alloy were bioactive.

  8. Microstructure and Mechanical Properties of Wide-gap Brazed Joints of K465 Alloy Using Cobalt-base Brazing Alloy

    OpenAIRE

    PAN Hui; ZHAO Haisheng

    2017-01-01

    Vacuum brazing of K465 superalloy was carried out by using Co45NiCrWB cobalt-base filler metal at 1220 ℃ for different holding time, and the joint clearance was 0.5 mm pre-filled with FGH95 nickel-base superalloy powder. The effect of the structural constitution of brazed different holding time of temperature on the brazed joint microstructure and properties. The results show that the brazing seam is composed of alloy powder particles and borides among them. It is two-phase structure of γ and...

  9. Effect of reduced cobalt contents on hot isostatically pressed powder metallurgy U-700 alloys

    Science.gov (United States)

    Harf, F. H.

    1982-01-01

    The effect of reducing the cobalt content of prealloyed powders of UDIMET 700 (U-700) alloys to 12.7, 8.6, 4.3, and 0% was examined. The powders were hot isostatically pressed into billets, which were given heat treatments appropriate for turbine disks, namely partial solutioning at temperatures below the gamma prime solvus and four step aging treatments. Chemical analyses, metallographic examinations, and X-ray diffraction measurements were performed on the materials. Minor effects on gamma prime content and on room temperature and 650 C tensile properties were observed. Creep rupture lives at 650 C reached a maximum at the 8.4% concentration, while at 760 C a maximum in life was reached at the 4.3% cobalt level. Minimum creep rates increased with decreasing cobalt content at both test temperatures. Extended exposures at 760 and 815 C resulted in decreased tensile strengths and rupture lives for all alloys. Evidence of sigma phase formation was also found.

  10. Effect of alloying Ni-Mn-Ga with Cobalt on thermal and structural properties

    Science.gov (United States)

    Rolfs, K.; Wimpory, R. C.; Petry, W.; Schneider, R.

    2010-11-01

    Materials showing a large magnetic field induced strain can potentially substitute giant magnetostrictive materials as well as piezoelectrical ceramics in actuating devices. However the magnetic shape memory alloys face several problems for an industrial application. Besides the well known brittleness the temperature-range is still limited due to the structural and magnetic phase transition around 75°C. By alloying one of the most common systems Ni-Mn-Ga with 4.8 at% and 6 at% Cobalt the Martensite temperature was increased up to 422K and the Curie temperature up to 432K. Neutron diffraction experiments were performed on these Ni-Mn-Ga-Co single crystalline samples at room temperature, which show the existence of two different non-modulated martensitic structures. Dependent on the composition, a tetragonal and an orthorhombic structure in single crystalline samples were verified. Furthermore intermartenstic phase transitions above room temperature were determined in several samples alloyed with 6 at% cobalt. A temperature dependent measurement of the structure of Ni44.6Mn29.1Ga20.1Co6.2 showed an orthorhombic phase from room temperature up to 379K changing to a tetragonal intermartensitic phase before reaching the austenitic phase above 389K.

  11. Corrosion resistance improvement of titanium base alloys

    Directory of Open Access Journals (Sweden)

    Mihai V. Popa

    2010-01-01

    Full Text Available The corrosion resistance of the new Ti-6Al-4V-1Zr alloy in comparison with ternary Ti-6Al-4V alloy in Ringer-Brown solution and artificial Carter-Brugirard saliva of different pH values was studied. In Ringer-Brown solution, the new alloy presented an improvement of all electrochemical parameters due to the alloying with Zr; also, impedance spectra revealed better protective properties of its passive layer. In Carter-Brugirard artificial saliva, an increase of the passive film thickness was proved. Fluoride ions had a slight negative influence on the corrosion and ion release rates, without to affect the very good stability of the new Ti-6Al-4V-1Zr alloy.

  12. Zirconium alloy barrier having improved corrosion resistance

    International Nuclear Information System (INIS)

    Adamson, R.B.; Rosenbaum, H.S.

    1983-01-01

    A nuclear fuel element for use in the core of a nuclear reactor has a composite cladding container having a substrate and a dilute zirconium alloy liner bonded to the inside surface of the substrate. The dilute zirconium alloy liner forms about 1 to about 20 percent of the thickness of the cladding and is comprised of zirconium and a metal selected from the group consisting of iron, chromium, iron plus chromium, and copper. The dilute zirconium alloy liner shields the substrate from impurities or fission products from the nuclear fuel material and protects the substrate from stress corrosion and stress cracking. The dilute zirconium alloy liner displays greater corrosion resistance, especially to oxidation by hot water or steam than unalloyed zirconium. The substrate material is selected from conventional cladding materials, and preferably is a zirconium alloy. (author)

  13. Influence of Cobalt on the Adhesion Strength of Polycrystalline Diamond Coatings on WC-Co Hard Alloys

    Science.gov (United States)

    Linnik, S. A.; Gaidaichuk, A. V.; Okhotnikov, V. V.

    2018-02-01

    The influence of cobalt on the phase composition and adhesion strength of polycrystalline diamond coatings has been studied using scanning electron microscopy, Raman spectroscopy, and X-ray microanalysis. The coatings have been deposited on WC-Co hard alloy substrates in glow discharge plasma. It has been found that the catalytic amorphization of carbon only takes place during the direct synthesis of the diamond coating, when the cobalt vapor pressure over the substrate is high and the cobalt-related degradation of the synthesized diamond is absent.

  14. Corrosion behaviour of cobalt-chromium dental alloys doped with precious metals.

    Science.gov (United States)

    Reclaru, Lucien; Lüthy, Heinz; Eschler, Pierre-Yves; Blatter, Andreas; Susz, Christian

    2005-07-01

    Precious metal based dental alloys generally exhibit a superior corrosion resistance, in particular enhanced resistance to pitting and crevice corrosion, compared to non-precious metal based alloys such as CoCr alloys. A new generation of Co-Cr alloys enriched with precious metals (Au, Pt, Ru) have now appeared on the market. The goal of this study was to clarify the effect of the precious metals additions on the corrosion behaviour of such alloys. Various commercial alloys with different doping levels were tested by electrochemical techniques in two different milieus based on the Fusayama artificial saliva and an electrolyte containing NaCl. Open circuit potentials, corrosion currents, polarization resistances, and crevices potentials were determined for the various alloys and completed by a coulometric analysis of the potentiodynamic curves. In addition, the microstructures were characterised by metallography and phase compositions analysed by EDX. The results show that the presence of precious metals can deteriorate the corrosion behaviour of Co-Cr alloys in a significant way. Gold doping, in particular, produces heterogeneous microstructures that are vulnerable to corrosive attack.

  15. Creep deformation of a soft magnetic iron-cobalt alloy

    Science.gov (United States)

    Fingers, R. T.; Coate, J. E.; Dowling, N. E.

    1999-04-01

    The U.S. Air Force is in the process of developing magnetic bearings, as well as an aircraft integrated power unit and an internal starter/generator for main propulsion engines. These developments are the driving force for the new emphasis on the development of high saturation, low loss magnets capable of maintaining structural integrity in high stress and high temperature environments. It is this combination of desired material characteristics that is the motivation of this effort to measure, model, and predict the creep behavior of such advanced magnetic materials. Hiperco® Alloy 50HS, manufactured by Carpenter Technology Corporation, is one of the leading candidates for these applications. Material specimens were subjected to a battery of mechanical tests in order to study and characterize their behaviors. Tensile tests provided stress versus strain behaviors that clearly indicated: a yield point, a heterogeneous deformation described as Lüders elongation, the Portevin-LeChatelier effect at elevated temperatures, and most often a section of homogeneous deformation that concluded with necking and fracture. Creep testing indicated three distinct types of behavior. Two types resembled a traditional response with primary, secondary, and tertiary stages; while the third type can be characterized by an abrupt increase in strain rate that acts as a transition from one steady-state behavior to another. The relationships between the tensile and creep responses are discussed. Analyses of the mechanical behavior include double linear regression of empirically modeled data, and constant strain rate testing to bridge the tensile and creep test parameters.

  16. Trunnion Failure of the Recalled Low Friction Ion Treatment Cobalt Chromium Alloy Femoral Head.

    Science.gov (United States)

    Urish, Kenneth L; Hamlin, Brian R; Plakseychuk, Anton Y; Levison, Timothy J; Higgs, Genymphas B; Kurtz, Steven M; DiGioia, Anthony M

    2017-09-01

    Gross trunnion failure (GTF) is a rare complication in total hip arthroplasty (THA) reported across a range of manufacturers. Specific lots of the Stryker low friction ion treatment (LFIT) anatomic cobalt chromium alloy (CoCr) V40 femoral head were recalled in August 2016. In part, the recall was based out of concerns for disassociation of the femoral head from the stem and GTF. We report on 28 patients (30 implants) with either GTF (n = 18) or head-neck taper corrosion (n = 12) of the LFIT CoCr femoral head and the Accolade titanium-molybdenum-zirconium-iron alloy femoral stems. All these cases were associated with adverse local tissue reactions requiring revision of the THA. In our series, a conservative estimate of the incidence of failure was 4.7% (n = 636 total implanted) at 8.0 ± 1.4 years from the index procedure. Failures were associated with a high-offset 127° femoral stem neck angle and increased neck lengths; 43.3% (13 of 30) of the observed failures included implant sizes outside the voluntary recall (27.8% [5 of 18] of the GTF and 75.0% [8 of 12] of the taper corrosion cases). Serum cobalt and chromium levels were elevated (cobalt: 8.4 ± 7.0 μg/mL; chromium: 3.4 ± 3.3 μ/L; cobalt/chromium ratio: 3.7). The metal artifact reduction sequence magnetic resonance imaging demonstrated large cystic fluid collections typical with adverse local tissue reactions. During revision, a pseudotumor was observed in all cases. Pathology suggested a chronic inflammatory response. Impending GTF could be diagnosed based on aspiration of black synovial fluid and an oblique femoral head as compared with the neck taper on radiographs. In our series of the recalled LFIT CoCr femoral head, the risk of impending GTF or head-neck taper corrosion should be considered as a potential diagnosis in a painful LFIT femoral head and Accolade titanium-molybdenum-zirconium-iron alloy THA with unknown etiology. Almost half of the failures we observed included sizes outside of the

  17. Magnetic properties of exchange-coupled trilayers of amorphous rare-earth-cobalt alloys

    International Nuclear Information System (INIS)

    Wuechner, S.; Toussaint, J.C.; Voiron, J.

    1997-01-01

    From amorphous thin films from alloys of rare earths (Gd, Sm), yttrium or zirconium with cobalt we have prepared trilayers with very clean interfaces appropriate for the study of magnetic coupling. The sandwiches were typically Y-Co/Gd-Co/Y-Co and Sm-Co/X/Sm-Co ' (X=Gd-Co, Co-Zr, Co). The three individual layers are coupled magnetically by exchange interactions between cobalt moments throughout the entire sample. This coupling associated with the specific properties of the given alloy (magnetic moment, anisotropy, coercivity) leads to ferrimagnetic or ferromagnetic structures of the magnetization of adjacent layers and to novel magnetization processes. For systems consisting of magnetically hard external layers with different coercivities and a soft central layer (Sm-Co/X/Sm-Co ' , X=Gd-Co, Co-Zr), the influence of the central layer close-quote s thickness and type of the material on coupling and magnetization processes have been studied quantitatively. Numerical simulations using a one-dimensional model for describing the magnetization processes observed in sandwich systems fit the magnetization curves of these model systems particularly well. copyright 1997 The American Physical Society

  18. The comparison of corrosion resistance between Baosteel's alloy 690 tube and foreign alloy 690 tube

    International Nuclear Information System (INIS)

    Ma Mingjuan; Zhang Lefu; Li Yan

    2012-01-01

    Alloy 690 having excellent corrosion resistance is widely used for SG tubes. The intergranular corrosion and pitting corrosion resistance of Baosteel's alloy 690 tube, Country A alloy 690 tube and Country B alloy 690 tube have been analysed by comparison. It shows that: The intergranular corrosion of Baosteel's alloy 690 tube tested complied with ASTM G28 Standard could satisfy the technical requirement. However.some of Baosteel's alloy 690 tube in intergranular corrosion resistance had less performance than Country A. In addition, pitting corrosion tested with ASTM G48 Standard shown the Baosteel's alloy 690 tube better than Country B. (authors)

  19. Cobalt-chromium alloys in dentistry: An evaluation of metal ion release.

    Science.gov (United States)

    Lucchetti, Maria Claudia; Fratto, Giovanni; Valeriani, Federica; De Vittori, Elisabetta; Giampaoli, Saverio; Papetti, Patrizia; Romano Spica, Vincenzo; Manzon, Licia

    2015-10-01

    Metal ions released into the oral cavity from dental prosthesis alloys may damage the cellular metabolism or proliferation and cause hypersensitivity or allergies. The oral cavity environment is particularly prone to corrosion due to saliva, microorganisms, and pH variations. The purpose of this in vitro study was to evaluate the ion release of chromium, cobalt, and iron from the Co-Cr alloys used for traditionally cast and computer-aided design/computer-aided manufacturing dental devices after interaction with oral bacteria and different pH conditions. All specimens were prepared from currently available alloys, polished, and immersed in 3 different pH media (artificial saliva [pH 2.3] and 6.5% and 0.9% saline solution [pH 7.1]). Specimens were also incubated in the presence of the bacterium Eikenella corrodens. Solutions were analyzed with an atomic absorption spectrometer after 15 and 30 days in the chemical corrosion test and 30 days in the biocorrosion test to detect ions released in different solutions. An ANOVA test was used to evaluate statistically significant differences among the percentages of metal corrosion ion release values. The greatest amount of element release was seen after 30 days: 4.964 ppm of casting alloy, 2.642 ppm of milling alloy, and 2.351 ppm of laser metal sintering. With the exception of casting alloy under acidic conditions, no significant differences were found, even after exposure to bacteria. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  20. Mechanical failure of hydroxyapatite-coated titanium and cobalt-chromium-molybdenum alloy implants. An animal study

    DEFF Research Database (Denmark)

    Nimb, L; Gotfredsen, K; Steen Jensen, J

    1993-01-01

    a histological and biomechanical evaluation of HA-coated titanium and cobalt-chromium-molybdenum alloy implants in a non-weight-bearing model. Twelve cylindrical plugs were inserted into the medial femoral condyle on 6 mongrel dogs. HA-coatings of 80-120 microns thickness were applied to 6 Cr-Co-Mo implants...

  1. Composition tunable cobalt–nickel and cobalt–iron alloy nanoparticles below 10 nm synthesized using acetonated cobalt carbonyl

    NARCIS (Netherlands)

    van Schooneveld, Matti M.; Campos-Cuerva, Carlos; Pet, Jeroen; Meeldijk, Johannes D.; van Rijssel, Jos; Meijerink, Andries; Erne, Ben H.; de Groot, Frank M. F.

    A general organometallic route has been developed to synthesize CoxNi1-x and CoxFe1-x alloy nanoparticles with a fully tunable composition and a size of 4–10 nm with high yield. In contrast to previously reported synthesis methods using dicobalt octacarbonyl (Co2(CO)8), here the cobalt–cobalt bond

  2. [Energy dispersive spectrum analysis of surface compositions of selective laser melting cobalt-chromium alloy fabricated by different processing parameters].

    Science.gov (United States)

    Qian, Liang; Zeng, Li; Wei, Bin; Gong, Yao

    2015-06-01

    To fabricate selective laser melting cobalt-chromium alloy samples by different processing parameters, and to analyze the changes of energy dispersive spectrum(EDS) on their surface. Nine groups were set up by orthogonal experimental design according to different laser powers,scanning speeds and powder feeding rates(laser power:2500-3000 W, scanning speed: 5-15 mm/s, powder feeding rate: 3-6 r/min). Three cylinder specimens(10 mm in diameter and 3 mm in thickness) were fabricated in each group through Rofin DL 035Q laser cladding system using cobalt-chromium alloy powders which were developed independently by our group.Their surface compositions were then measured by EDS analysis. Results of EDS analysis of the 9 groups fabricated by different processing parameters(Co:62.98%-67.13%,Cr:25.56%-28.50%,Si:0.49%-1.23%) were obtained. They were similar to the compositions of cobalt-chromium alloy used in dental practice. According to EDS results, the surface compositions of the selective laser melting cobalt-chromium alloy samples are stable and controllable, which help us gain a preliminary sight into the range of SLM processing parameters. Supported by "973" Program (2012CB910401) and Research Fund of Science and Technology Committee of Shanghai Municipality (12441903001 and 13140902701).

  3. Sequential potentiometric complexometric redox determination of iron(III) and cobalt(II) with application to alloys.

    Science.gov (United States)

    Rao, B V; Gopinath, R

    1989-08-01

    A simple potentiometric method is presented for successive determination of iron(III) and cobalt(II) by complexometric titration of the iron(III) with EDTA at pH 2 and 40 degrees , followed by redox titration of the cobalt(II) complex with 1,10-phenanthroline or 2,2'-bipyridyl at pH 4-5 and 40 degrees , with gold(III). There is no interference in either determination from common metal ions other than copper(II), which severely affects the cobalt determination but can be removed by electrolysis. The method has been successfully applied to determination of iron and cobalt in Kovar and Alnico magnet alloys.

  4. Comparative Study Between Cobalt Chrome and Titanium Alloy Rods for Multilevel Spinal Fusion: Proximal Junctional Kyphosis More Frequently Occurred in Patients Having Cobalt Chrome Rods.

    Science.gov (United States)

    Han, Sanghyun; Hyun, Seung-Jae; Kim, Ki-Jeong; Jahng, Tae-Ahn; Kim, Hyun-Jib

    2017-07-01

    The use of titanium alloy (Ti) rods is frequently associated with rod fracture after spinal fixation. To address this issue, cobalt chrome (CoCr) rods, which are advantageous because of their greater strength and resistance to fatigue relative to Ti rods, have been introduced. The purpose of the present study was to compare radiographic outcomes after the use of Ti versus CoCr rods in a matched cohort of patients undergoing posterior spinal fusion for treatment of spinal instability. We retrospectively reviewed data from patients who had undergone spinal fusion involving more than 3 levels at a single institution between 2004 and 2015. Patients were matched for age, diagnosis, 3-column osteotomy, levels fused, and T score. Fifty patients with Ti rods were identified and appropriately matched to 50 consecutive patients with CoCr rods. The distributions of age at surgery, sex, diagnosis, 3-column osteotomy, levels fused, number of patients with previous surgical procedures, and T score did not significantly differ between the 2 groups. However, there were significant differences in length of follow-up (CoCr, 25.0 vs. Ti, 28.5 months; P < 0.001), fusion rate (CoCr, 45 [90%] vs. Ti, 33 [66%]; P = 0.004), occurrence of rod breakage (CoCr, 0 vs. T, 8 [16%]; P = 0.006), and junctional kyphosis (CoCr, 24 [46%] vs. Ti, 9 [18%]; P = 0.003). Our findings indicate that the use of CoCr rods is effective in ensuring stability of the posterior spinal construct and accomplishment of spinal fusion. Furthermore, our results indicate that junctional kyphosis may occur more frequently in CoCr systems than in Ti systems. Copyright © 2017 Elsevier Inc. All rights reserved.

  5. The role of cobalt on the creep of Waspaloy

    Science.gov (United States)

    Jarrett, R. N.; Chin, L.; Tien, J. K.

    1984-01-01

    Cobalt was systematically replaced with nickel in Waspaloy (which normally contains 13% Co) to determine the effects of cobalt on the creep behavior of this alloy. Effects of cobalt were found to be minimal on tensile strengths and microstructure. The creep resistance and the stress rupture resistance determined in the range from 704 to 760 C (1300 to 1400 C) were found to decrease as cobalt was removed from the standard alloy at all stresses and temperatures. Roughly a ten-fold drop in rupture life and a corresponding increase in minimum creep rate were found under all test conditions. Both the apparent creep activation energy and the matrix contribution to creep resistance were found to increase with cobalt. These creep effects are attributed to cobalt lowering the stacking fault energy of the alloy matrix. The creep resistance loss due to the removal of cobalt is shown to be restored by slightly increasing the gamma' volume fraction. Results are compared to a previous study on Udimet 700, a higher strength, higher gamma' volume fraction alloy with similar phase chemistry, in which cobalt did not affect creep resistance. An explanation for this difference in behavior based on interparticle spacing and cross-slip is presented.

  6. Ammonia synthesis with barium-promoted iron–cobalt alloys supported on carbon

    DEFF Research Database (Denmark)

    Hagen, Stefan; Barfod, Rasmus; Fehrmann, Rasmus

    2003-01-01

    Iron–cobalt alloys supported on carbon were investigated as ammonia synthesis catalysts. Barium was found to have a promoting effect for Fe with an optimum atomic ratio Ba/Fe of 0.35. At this Ba loading, a local maximum for the NH3 synthesis activity was found at 4 wt% Co by varying the Fe/Co ratio....... Samples containing only Co and no Fe, however, yielded by far the most active catalysts (7.0 μmol (NH3) g−1 s−1, 673 K, 10 bar). Barium was a very efficient promoter for Co, increasing the NH3 synthesis activity by more than two orders of magnitude compared to the unpromoted Co samples, while...

  7. Hydrogen Storage Studies of Palladium-Cobalt alloy nanoparticles dispersed Nitrogen Doped Graphene

    Science.gov (United States)

    Pullamsetty, Ashok; Sundara, Ramaprabhu

    Solid state hydrogen storage has significant importance in the present scenario of depleting conventional energy sources. Recent studies reveal that nanomaterials can play a significant role in the performance enhancement of energy conversion and storage device. Carbon based nanomaterials are considered as suitable candidates for hydrogen storage due to their high porosity, large surface area and high chemical stability. The two dimensional graphene, which has been discovered recently, consists of a single layer of atoms arranged in a honeycomb lattice, exhibits surface area. In the present work, we have been studied the hydrogen storage properties of Palladium-Cobalt alloy nanoparticles dispersed nitrogen doped graphene (Pd3Co/NG). Graphitic oxide was prepared by Hummers method and mixed with Palladium Cobalt and melamine precursors. The compound was reduced in hydrogen atmosphere at 500 °C for 5 h. Structural and micro-structural characterization of these samples has been carried out by X-ray diffraction pattern (XRD), Raman spectroscopy, scanning electron microscope (SEM), transmission electron microscopy (TEM) and X-ray photo electro spectroscopy (XPS). The hydrogen adsorption measurements were carried out for NG as well as Pd3Co/NG at different temperatures (25-100 °C) and pressures (5-40 bar) using a high pressure Sieverts apparatus. The material Pd3Co/NG exhibits high storage capacity compared to NG due to spillover mechanism and the results have been discussed.

  8. Sliding wear resistance of iron aluminides

    Indian Academy of Sciences (India)

    Unknown

    severe wear and erosion applications include cobalt- based alloys, high manganese stainless steels, and other chromium containing alloys. There is considerable inte- rest in replacing cobalt-based alloys for erosion resistance in nuclear power applications because of the problems with exposure of maintenance workers to ...

  9. Retention strength between veneering resin composites and laser-sintered cobalt-chromium alloy.

    Science.gov (United States)

    Kamada, Kohji; Taira, Yohsuke; Sumi, Tadateru; Sawase, Takashi

    2017-01-01

    The purpose of the present study was to evaluate the retention strength between a resin composite veneering material and three types of cobalt-chromium (Co-Cr) alloy substrates. Co-Cr alloy specimens with 81 retention devices (LSR), with 144 retention devices (LDR), and without retention device (LN) were fabricated using a laser-sintering system. The specimens were air-abraded with alumina, conditioned with a primer [Alloy primer (AP) or M.L. primer (ML)], and veneered with a light-polymerized resin composite (Gradia). Three control groups (LSR-N, LDR-N, and LN-N) without primer were also prepared. After 20,000 thermocycles in 4 and 60 °C water, tensile retention strengths were determined using a universal testing machine. Data were analyzed by analysis of variance and a post hoc Tukey-Kramer HSD test (α = 0.05, n = 8). The highest retention strengths were obtained in LSR-AP (28.3 MPa), LSR-ML (23.3 MPa), LDR-AP (26.9 MPa), and LDR-ML (27.8 MPa), and these values were not significantly different. In the absence of a retention device, the retention strengths were significantly different in the following order: LN-N (0.1 MPa) LDR-N (17.1 MPa). No significant difference was found between the numbers of retention devices, which were 81 and 144. In conclusion, the combined use of the primers and the retention devices is recommended when the laser-sintered Co-Cr alloy is veneered with the resin composite materials to maximize the retention strength.

  10. Effect of recasting on the thickness of metal-ceramic interface of nickel-chromium and cobalt-chromium alloys

    Directory of Open Access Journals (Sweden)

    Mirković Nemanja

    2008-01-01

    Full Text Available Introduction/Aim. This research was done to establish recasting effects of nickel-chromium and cobalt-chromium alloys on the thickness of their metal-ceramic interface in making fixed partial dentures. Metal-ceramic interface determines their functional integrity and prevents damages on ceramics during mastication. Investigation of metal-ceramic samples is supposed to show if base metal alloys for metalceramics are successfully recycled without any risk of reduction of metal-ceramic interface thickness. Methods. The research was performed as an experimental study. Per six metal-ceramic samples of nickel-chromium alloy (Wiron99 and cobalt-chromium alloy (Wirobond C were made each. Alloy residues were recycled through twelve casting generations with the addition of 50% of new alloy on the occasion of every recasting. Analysis Energy Dispersive X-ray (EDX (Oxford Instruments and Scanning Electon Microscop (SEM analysis (JEOL were used to determine thickness of metal-ceramic interface together with PC Software for quantification of visual information's (KVI POPOVAC. Results. Results of this research introduced significant differences between thickness of metal-ceramic interface in every examined recycle generation. Recasting had negative effect on thickness of metal-ceramic interface of the examined alloys. This research showed almost linear reduction of elastic modulus up to the 12th generation of recycling. Conclusion. Recasting of nickel-chromium and cobaltchromium alloys is not recommended because of reduced thickness of metal-ceramic interface of these alloys. Instead of recycling, the alloy residues should be returned to the manufacturers.

  11. Microstructure and Mechanical Properties of Wide-gap Brazed Joints of K465 Alloy Using Cobalt-base Brazing Alloy

    Directory of Open Access Journals (Sweden)

    PAN Hui

    2017-06-01

    Full Text Available Vacuum brazing of K465 superalloy was carried out by using Co45NiCrWB cobalt-base filler metal at 1220 ℃ for different holding time, and the joint clearance was 0.5 mm pre-filled with FGH95 nickel-base superalloy powder. The effect of the structural constitution of brazed different holding time of temperature on the brazed joint microstructure and properties. The results show that the brazing seam is composed of alloy powder particles and borides among them. It is two-phase structure of γ and γ' with a few small blocks of borides in the powder particles, and there exists phases rich in Cr, W and Nb elements. The powder particles are growing along the holding time during the brazing process, while their combination is expanded. It is good for stress rapture properties of joints that borides was fine in brazing seam with more superalloy powder and proper holding time. And the joints brazed for 30-60 min show higher stress rapture properties.

  12. Evaluation of the mechanical properties and porcelain bond strength of cobalt-chromium dental alloy fabricated by selective laser melting.

    Science.gov (United States)

    Wu, Lin; Zhu, Haiting; Gai, Xiuying; Wang, Yanyan

    2014-01-01

    Limited information is available regarding the microstructure and mechanical properties of dental alloy fabricated by selective laser melting (SLM). The purpose of this study was to evaluate the mechanical properties of a cobalt-chromium (Co-Cr) dental alloy fabricated by SLM and to determine the correlation between its microstructure and mechanical properties and its porcelain bond strength. Five metal specimens and 10 metal ceramic specimens were fabricated to evaluate the mechanical properties of SLM Co-Cr dental alloy (SLM alloy) with a tensile test and its porcelain bond strength with a 3-point bending test. The relevant properties of the SLM alloy were compared with those of the currently used Co-Cr dental alloy fabricated with conventional cast technology (cast alloy). The Student t test was used to compare the results of the SLM alloy and the cast alloy (α=.05). The microstructure of the SLM alloy was analyzed with a metallographic microscope; the metal ceramic interface of the SLM porcelain bonded alloy was studied with scanning electron microscopy, energy dispersive x-ray spectroscopy, and an electron probe microanalyzer. Both the mean (standard deviation) yield strength (884.37 ± 8.96 MPa) and tensile strength (1307.50 ±10.65 MPa) of the SLM alloy were notably higher than yield strength (568.10 ± 30.94 MPa) and tensile strength (758.73 ± 25.85 MPa) of the currently used cast alloy, and the differences were significant (P.05). Microstructure analysis suggested that the SLM alloy had a dense and obviously orientated microstructure, which led to excellent mechanical properties. Analysis from scanning electron microscopy, energy dispersive x-ray spectroscopy, and the electron probe microanalyzer indicated that the SLM alloy had an intermediate layer with elemental interpenetration between the alloy and the porcelain, which resulted in an improved bonding interface. Compared with the currently used cast alloy, SLM alloy possessed improved mechanical

  13. Effects of long-time elevated temperature exposures on hot-isostatically-pressed power-metallurgy Udimet 700 alloys with reduced cobalt contents

    Science.gov (United States)

    Hart, F. H.

    1984-01-01

    Because almost the entire U.S. consumption of cobalt depends on imports, this metal has been designated "strategic'. The role and effectiveness of cobalt is being evaluated in commercial nickel-base superalloys. Udiment 700 type alloys in which the cobalt content was reduced from the normal 17% down to 12.7%, 8.5%, 4.3%, and 0% were prepared by standard powder metallurgy techniques and hot isostatically pressed into billets. Mechanical testing and microstructural investigations were performed. The mechanical properties of alloys with reduced cobalt contents which were heat-treated identically were equal or better than those of the standard alloy, except that creep rates tended to increase as cobalt was reduced. The effects of long time exposures at 760 C on mechanical properties and at 760 C and 845 C on microstructures were determined. Decreased tensile properties and shorter rupture lives with increased creep rates were observed in alloy modifications. The exposures caused gamma prime particle coarsening and formation of sigma phase in the alloys with higher cobalt contents. Exposure at 845 C also reduced the amount of MC carbides.

  14. Effects of cobalt on structure, microchemistry and properties of a wrought nickel-base superalloy

    Science.gov (United States)

    Jarrett, R. N.; Tien, J. K.

    1982-01-01

    The effect of cobalt on the basic mechanical properties and microstructure of wrought nickel-base superalloys has been investigated experimentally by systematically replacing cobalt by nickel in Udimet 700 (17 wt% Co) commonly used in gas turbine (jet engine) applications. It is shown that the room temperature tensile yield strength and tensile strength only slightly decrease in fine-grained (disk) alloys and are basically unaffected in coarse-grained (blading) alloys as cobalt is removed. Creep and stress rupture resistances at 760 C are found to be unaffected by cobalt level in the blading alloys and decrease sharply only when the cobalt level is reduced below 8 vol% in the disk alloys. The effect of cobalt is explained in terms of gamma prime strengthening kinetics.

  15. Cobalt Alloy Implant Debris Induces Inflammation and Bone Loss Primarily through Danger Signaling, Not TLR4 Activation: Implications for DAMP-ening Implant Related Inflammation.

    Directory of Open Access Journals (Sweden)

    Lauryn Samelko

    Full Text Available Cobalt alloy debris has been implicated as causative in the early failure of some designs of current total joint implants. The ability of implant debris to cause excessive inflammation via danger signaling (NLRP3 inflammasome vs. pathogen associated pattern recognition receptors (e.g. Toll-like receptors; TLRs remains controversial. Recently, specific non-conserved histidines on human TLR4 have been shown activated by cobalt and nickel ions in solution. However, whether this TLR activation is directly or indirectly an effect of metals or secondary endogenous alarmins (danger-associated molecular patterns, DAMPs elicited by danger signaling, remains unknown and contentious. Our study indicates that in both a human macrophage cell line (THP-1 and primary human macrophages, as well as an in vivo murine model of inflammatory osteolysis, that Cobalt-alloy particle induced NLRP3 inflammasome danger signaling inflammatory responses were highly dominant relative to TLR4 activation, as measured respectively by IL-1β or TNF-α, IL-6, IL-10, tissue histology and quantitative bone loss measurement. Despite the lack of metal binding histidines H456 and H458 in murine TLR4, murine calvaria challenge with Cobalt alloy particles induced significant macrophage driven in vivo inflammation and bone loss inflammatory osteolysis, whereas LPS calvaria challenge alone did not. Additionally, no significant increase (p500pg/mL. Therefore, not only do the results of this investigation support Cobalt alloy danger signaling induced inflammation, but under normal homeostasis low levels of hematogenous PAMPs (<2pg/mL from Gram-negative bacteria, seem to have negligible contribution to the danger signaling responses elicited by Cobalt alloy metal implant debris. This suggests the unique nature of Cobalt alloy particle bioreactivity is strong enough to illicit danger signaling that secondarily activate concomitant TLR activation, and may in part explain Cobalt particulate

  16. Cobalt Alloy Implant Debris Induces Inflammation and Bone Loss Primarily through Danger Signaling, Not TLR4 Activation: Implications for DAMP-ening Implant Related Inflammation

    Science.gov (United States)

    Samelko, Lauryn; Landgraeber, Stefan; McAllister, Kyron; Jacobs, Joshua; Hallab, Nadim James

    2016-01-01

    Cobalt alloy debris has been implicated as causative in the early failure of some designs of current total joint implants. The ability of implant debris to cause excessive inflammation via danger signaling (NLRP3 inflammasome) vs. pathogen associated pattern recognition receptors (e.g. Toll-like receptors; TLRs) remains controversial. Recently, specific non-conserved histidines on human TLR4 have been shown activated by cobalt and nickel ions in solution. However, whether this TLR activation is directly or indirectly an effect of metals or secondary endogenous alarmins (danger-associated molecular patterns, DAMPs) elicited by danger signaling, remains unknown and contentious. Our study indicates that in both a human macrophage cell line (THP-1) and primary human macrophages, as well as an in vivo murine model of inflammatory osteolysis, that Cobalt-alloy particle induced NLRP3 inflammasome danger signaling inflammatory responses were highly dominant relative to TLR4 activation, as measured respectively by IL-1β or TNF-α, IL-6, IL-10, tissue histology and quantitative bone loss measurement. Despite the lack of metal binding histidines H456 and H458 in murine TLR4, murine calvaria challenge with Cobalt alloy particles induced significant macrophage driven in vivo inflammation and bone loss inflammatory osteolysis, whereas LPS calvaria challenge alone did not. Additionally, no significant increase (p500pg/mL). Therefore, not only do the results of this investigation support Cobalt alloy danger signaling induced inflammation, but under normal homeostasis low levels of hematogenous PAMPs (<2pg/mL) from Gram-negative bacteria, seem to have negligible contribution to the danger signaling responses elicited by Cobalt alloy metal implant debris. This suggests the unique nature of Cobalt alloy particle bioreactivity is strong enough to illicit danger signaling that secondarily activate concomitant TLR activation, and may in part explain Cobalt particulate associated

  17. Studies on neutron irradiation effects of iron alloys and nickel-base heat resistant alloys

    International Nuclear Information System (INIS)

    Watanabe, Katsutoshi

    1987-09-01

    The present paper describes the results of neutron irradiation effects on iron alloys and nickel-base heat resistant alloys. As for the iron alloys, irradiation hardening and embrittlement were investigated using internal friction measurement, electron microscopy and tensile testings. The role of alloying elements was also investigated to understand the irradiation behavior of iron alloys. The essential factors affecting irradiation hardening and embrittlement were thus clarified. On the other hand, postirradiation tensile and creep properties were measured of Hastelloy X alloy. Irradiation behavior at elevated temperatures is discussed. (author)

  18. Effect of Alkaline Peroxides on the Surface of Cobalt Chrome Alloy: An In Vitro Study.

    Science.gov (United States)

    Vasconcelos, Glenda Lara Lopes; Curylofo, Patricia Almeida; Raile, Priscilla Neves; Macedo, Ana Paula; Paranhos, Helena Freitas Oliveira; Pagnano, Valeria Oliveira

    2018-03-24

    Removable denture hygiene care is very important for the longevity of the rehabilitation treatment; however, it is necessary to analyze the effects that denture cleansers can cause on the surfaces of prostheses. Thus, this study evaluated the effect of alkaline peroxide-effervescent tablets on the surface of cobalt-chromium alloys (Co-Cr) used in removable partial dentures. Circular metallic specimens (12 × 3 mm) were fabricated and were immersed (n = 16) in: control, Polident 3 Minute (P3M), Steradent (S), Efferdent (E), Polident for Partials (PFP), and Corega Tabs (CT). The surface roughness (μm) (n = 10) was measured before and after periods of cleanser immersion corresponding to 0.5, 1, 2, 3, 4, and 5 years. Ion release was analyzed (n = 5) for Co, Cr, and molybdenum (Mo). Scanning electron microscopy (SEM) analysis and an Energy-dispersive X-ray spectroscopy (EDS) were conducted in one specimen. The surface roughness data were statistically analyzed (α = 0.05) with the Kruskal-Wallis test to compare the solutions, and the Friedman test compared the immersion durations. Ion release analysis was performed using 2-way ANOVA and Tukey's test. There was no significant surface roughness difference when comparing the solutions (p > 0.05) and the immersion durations (p = 0.137). Regarding ion release (μg/L), CT, E, and control produced a greater release of Co ions than S (p < 0.05). CT produced a greater release of Cr ions than control, S, and P3M (p < 0.05). Finally, E caused the greatest release of Mo ions (p < 0.05). SEM confirmed that the solutions did not damage the surfaces and EDS confirmed that there were no signs of oxidation. The various solutions tested did not have any deleterious effects on the Co-Cr alloy surface. Steradent, however, presented the smallest ionic release. © 2018 by the American College of Prosthodontists.

  19. Deformation behavior of NiAl-based alloys containing iron, cobalt, and hafnium

    Science.gov (United States)

    Pank, D. R.; Koss, D. A.; Nathal, M. V.

    1989-01-01

    The effects of alloying additions on the mechanical properties of the B2 intermetallic NiAl have been investigated in both the melt-spun ribbon and consolidated, bulk form. The study is based on a matrix of NiAl-based alloys with up to 20 at. pct Co and Fe additions and with reduced Al levels in the range of 30-40 at. pct. Characterization of the melt-spun ribbon by optical and scanning electron microscopy indicates a range of microstructures, including single-phase beta, gamma-prime necklace phase surrounding either martensitic or beta grains, and a mixture of equiaxed martensitic and gamma-prime grains. Bend ductility is present in melt-spun and annealed ribbons exhibiting the gamma-prime necklace structure and in a single-phase beta material containing 20 at. pct Fe. The analysis of compressive flow behavior on consolidated, bulk specimens indicates that the single-phase beta alloys exhibit a continuous decrease in yield stress with increasing temperature and profuse microcracking at grain boundaries. In contrast, multiphase (gamma-prime + either martensite or beta) alloys tend to display a peak in flow stress between 600 and 800 K, with little or no signs of microcracking. In general, heat treatments which convert the martensitic grains to beta + gamma-prime result in improved strength at temperatures above 600 K and better resistance to crack initiation.

  20. CORROSION RESISTANCE OF DYNAMIC LOADED CAST ALLOY AS12

    Directory of Open Access Journals (Sweden)

    A. A. Andrushevich

    2017-01-01

    Full Text Available The assessment of influence of powder particles in the mode of super deep penetration (SDP on change of corrosion resistance of aluminum cast alloy AK12 is executed. The aluminum alloy reinforced by fiber zones with the reconstructed structure has the increased corrosion resistance.

  1. Electrical resistivity of liquid Ag-Au alloy

    International Nuclear Information System (INIS)

    Anis Alam, M.; Tomak, M.

    1983-01-01

    Calculations of the dependence of the electrical resistivity in liquid Ag-Au binary alloy on composition are reported. The structure of the binary alloy is described as a hard-sphere system. A one-parameter local pseudopotential, which incorporates s-d hybridization effects phenomenologically, is employed in the resistivity calculation. A reasonable agreement with experimental trend is observed. (author)

  2. Microstructure of Al2O3 nanocrystalline/cobalt-based alloy composite coatings by laser deposition

    International Nuclear Information System (INIS)

    Li Mingxi; He Yizhu; Yuan Xiaomin; Zhang Shihong

    2006-01-01

    Composite coatings, made of nano-Al 2 O 3 /cobalt-based alloy, produced by a 5-kW CO 2 laser on Ni-based superalloy were investigated. The coatings were examined to reveal their microstructure using optical microscope, scanning electron microscope, transmission electron microscope and X-ray diffraction instrument. The results showed that some equilibrium or non-equilibrium phases, such as γ-Co, Cr 23 C 6 , CoAl 2 O 4 , Al 2 O 3 and ε-Co existed in the coatings. Fine and short dendritic microstructure and columnar to equiaxed transition occurred by adding nano-Al 2 O 3 particle. With the increase of nano-materials (1%, mass fraction), fully equiaxed crystallization appeared. These were contributed to that nano-Al 2 O 3 particles acted as new nucleation site and rapid solidification of the melted pool. The results also showed inhomogeneous dispersion of nano-Al 2 O 3 that resulted in the formation of ε-Co phase in the coatings. The sub-microstructure of the clad was stacking fault. The mechanism of formation of equiaxed grains was also analyzed

  3. Ammonia synthesis with barium-promoted iron–cobalt alloys supported on carbon

    DEFF Research Database (Denmark)

    Hagen, Stefan; Barfod, Rasmus; Fehrmann, Rasmus

    2003-01-01

    Iron–cobalt alloys supported on carbon were investigated as ammonia synthesis catalysts. Barium was found to have a promoting effect for Fe with an optimum atomic ratio Ba/Fe of 0.35. At this Ba loading, a local maximum for the NH3 synthesis activity was found at 4 wt% Co by varying the Fe/Co ratio...... it was not as effective for Fe. Power-law kinetic investigation revealed that, compared to the commercial Fe-based NH3 catalyst, the Ba–Co/C samples showed a lower inhibition by NH3 and were more active under ordinary ammonia synthesis conditions........ Samples containing only Co and no Fe, however, yielded by far the most active catalysts (7.0 μmol (NH3) g−1 s−1, 673 K, 10 bar). Barium was a very efficient promoter for Co, increasing the NH3 synthesis activity by more than two orders of magnitude compared to the unpromoted Co samples, while...

  4. Cobalt Alloy Implant Debris Induces Inflammation and Bone Loss Primarily through Danger Signaling, Not TLR4 Activation: Implications for DAMP-ening Implant Related Inflammation.

    Science.gov (United States)

    Samelko, Lauryn; Landgraeber, Stefan; McAllister, Kyron; Jacobs, Joshua; Hallab, Nadim James

    2016-01-01

    Cobalt alloy debris has been implicated as causative in the early failure of some designs of current total joint implants. The ability of implant debris to cause excessive inflammation via danger signaling (NLRP3 inflammasome) vs. pathogen associated pattern recognition receptors (e.g. Toll-like receptors; TLRs) remains controversial. Recently, specific non-conserved histidines on human TLR4 have been shown activated by cobalt and nickel ions in solution. However, whether this TLR activation is directly or indirectly an effect of metals or secondary endogenous alarmins (danger-associated molecular patterns, DAMPs) elicited by danger signaling, remains unknown and contentious. Our study indicates that in both a human macrophage cell line (THP-1) and primary human macrophages, as well as an in vivo murine model of inflammatory osteolysis, that Cobalt-alloy particle induced NLRP3 inflammasome danger signaling inflammatory responses were highly dominant relative to TLR4 activation, as measured respectively by IL-1β or TNF-α, IL-6, IL-10, tissue histology and quantitative bone loss measurement. Despite the lack of metal binding histidines H456 and H458 in murine TLR4, murine calvaria challenge with Cobalt alloy particles induced significant macrophage driven in vivo inflammation and bone loss inflammatory osteolysis, whereas LPS calvaria challenge alone did not. Additionally, no significant increase (p500pg/mL). Therefore, not only do the results of this investigation support Cobalt alloy danger signaling induced inflammation, but under normal homeostasis low levels of hematogenous PAMPs (alloy metal implant debris. This suggests the unique nature of Cobalt alloy particle bioreactivity is strong enough to illicit danger signaling that secondarily activate concomitant TLR activation, and may in part explain Cobalt particulate associated inflammatory and toxicity-like reactions of specific orthopedic implants.

  5. TA [B] Predicting Microstructure-Creep Resistance Correlation in High Temperature Alloys over Multiple Time Scales

    Energy Technology Data Exchange (ETDEWEB)

    Tomar, Vikas [Purdue Univ., West Lafayette, IN (United States)

    2017-03-06

    DoE-NETL partnered with Purdue University to predict the creep and associated microstructure evolution of tungsten-based refractory alloys. Researchers use grain boundary (GB) diagrams, a new concept, to establish time-dependent creep resistance and associated microstructure evolution of grain boundaries/intergranular films GB/IGF controlled creep as a function of load, environment, and temperature. The goal was to conduct a systematic study that includes the development of a theoretical framework, multiscale modeling, and experimental validation using W-based body-centered-cubic alloys, doped/alloyed with one or two of the following elements: nickel, palladium, cobalt, iron, and copper—typical refractory alloys. Prior work has already established and validated a basic theory for W-based binary and ternary alloys; the study conducted under this project extended this proven work. Based on interface diagrams phase field models were developed to predict long term microstructural evolution. In order to validate the models nanoindentation creep data was used to elucidate the role played by the interface properties in predicting long term creep strength and microstructure evolution.

  6. Synthesis and characterization of mixtures of cobalt and titanium oxides by mechanical alloyed and Sol-Gel

    International Nuclear Information System (INIS)

    Basurto S, R.; Bonifacio M, J.; Fernandez V, S. M.

    2009-01-01

    The mechanical alloyed techniques continued by combustion and Sol-Gel method, were used for the synthesis of CoTiO 3 . With the first technique was used Co 3 O 4 obtained in a balls mill SPEX in argon atmosphere, using cobalt nitrate and urea, the combustion is realized at 400 and 500 C, the characterization by X-ray diffraction showed the obtaining of the valence oxide mixed of cobalt with crystallite size from 10 to 12.5 nm and the particle size of 60 to 75 nm was obtained by scanning electron microscopy. To prepare the CoTiO 3 , the obtained Co 3 O 4 was mixed with TiO 2 on a relationship in weight (1:1) and with a milling time of 2.5 h and the combustion at 800 C. the mixed oxide of titanium cobalt was also obtained by the Sol-Gel technique starting from cobalt chloride and titanium propoxide in acetic-water acid, the gel is burned to temperature of 300, 500, 700 and 900 C, finding that this last temperature it is that provides the compound with crystalline size from 50 to 75 nm. (Author)

  7. Cobalt-alloy implant debris induce HIF-1α hypoxia associated responses: a mechanism for metal-specific orthopedic implant failure.

    Directory of Open Access Journals (Sweden)

    Lauryn Samelko

    Full Text Available The historical success of orthopedic implants has been recently tempered by unexpected pathologies and early failures of some types of Cobalt-Chromium-Molybdenum alloy containing artificial hip implants. Hypoxia-associated responses to Cobalt-alloy metal debris were suspected as mediating this untoward reactivity at least in part. Hypoxia Inducible Factor-1α is a major transcription factor involved in hypoxia, and is a potent coping mechanism for cells to rapidly respond to changing metabolic demands. We measured signature hypoxia associated responses (i.e. HIF-1α, VEGF and TNF-α to Cobalt-alloy implant debris both in vitro (using a human THP-1 macrophage cell line and primary human monocytes/macrophages and in vivo. HIF-1α in peri-implant tissues of failed metal-on-metal implants were compared to similar tissues from people with metal-on-polymer hip arthroplasties, immunohistochemically. Increasing concentrations of cobalt ions significantly up-regulated HIF-1α with a maximal response at 0.3 mM. Cobalt-alloy particles (1 um-diameter, 10 particles/cell induced significantly elevated HIF-1α, VEGF, TNF-α and ROS expression in human primary macrophages whereas Titanium-alloy particles did not. Elevated expression of HIF-1α was found in peri-implant tissues and synovial fluid of people with failing Metal-on-Metal hips (n = 5 compared to failed Metal-on-Polymer articulating hip arthroplasties (n = 10. This evidence suggests that Cobalt-alloy, more than other metal implant debris (e.g. Titanium alloy, can elicit hypoxia-like responses that if unchecked can lead to unusual peri-implant pathologies, such as lymphocyte infiltration, necrosis and excessive fibrous tissue growths.

  8. The Cytotoxicity and Genotoxicity of Particulate and Soluble Cobalt in Human Urothelial Cells.

    Science.gov (United States)

    Speer, Rachel M; The, Therry; Xie, Hong; Liou, Louis; Adam, Rosalyn M; Wise, John Pierce

    2017-11-01

    Cobalt use is increasing particularly due to its use as one of the primary metals in cobalt-chromium-molybdenum (CoCrMo) metal-on-metal prosthetics. CoCrMo is a high-strength, wear-resistant alloy with reduced risk for prosthetic loosening and device fracture. More than 500,000 people receive hip implants each year in the USA which puts them at potential risk for exposure to metal ions and particles released by the prosthetic implants. Data show cobalt ions released from prosthetics reach the bloodstream and accumulate in the bladder. As patients with failed hip implants show increased urinary and blood cobalt levels, no studies have considered the effects of cobalt on human urothelial cells. Accordingly, we investigated the cytotoxic and genotoxic effects of particulate and soluble cobalt in urothelial cells. Exposure to both particulate and soluble cobalt resulted in a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ions. Based on intracellular cobalt ion levels, we found, when compared to particulate cobalt, soluble cobalt was more cytotoxic, but induced similar levels of genotoxicity. Interestingly, at similar intracellular cobalt ion concentrations, soluble cobalt induced cell cycle arrest indicated by a lack of metaphases not observed after particulate cobalt treatment. These data indicate that cobalt compounds are cytotoxic and genotoxic to human urothelial cells and solubility may play a key role in cobalt-induced toxicity.

  9. Effect of oxidation heat treatment on the bond strength between a ceramic and cast and milled cobalt-chromium alloys.

    Science.gov (United States)

    Li, Jieyin; Ye, Xiuhua; Li, Bohua; Liao, Juankun; Zhuang, Peilin; Ye, Jiantao

    2015-08-01

    There is a dearth of dental scientific literature on the effect of different oxidation heat treatments (OHTs) (as surface pretreatments) on the bonding performance of cast and milled cobalt-chromium (CoCr) alloys. The objective of this study was to evaluate the effect of different OHTs on the bond strength between a ceramic and cast and milled CoCr alloys. Cobalt-chromium metallic specimens were prepared using either a cast or a milled method. Specimens were subjected to four different OHT methods: without OHT; OHT under normal atmospheric pressure; OHT under vacuum; and OHT under vacuum followed by sandblasting. The metal-ceramic bond strength was evaluated using a three-point bending test according to ISO9693. Scanning electron microscopy and energy-dispersive spectroscopy were used to study the specimens' microstructure and elemental composition. The bond strength was not affected by the CoCr manufacturing method. Oxidation heat treatment performed under normal atmospheric pressure resulted in the highest bond strength. The concentration of oxygen on the alloy surfaces varied with the different pretreatment methods in the following order: OHT under normal atmospheric pressure > OHT under vacuum > without OHT ≈ OHT under vacuum followed by sandblasting. © 2015 Eur J Oral Sci.

  10. Cobalt-chromium-molybdenum alloy causes metal accumulation and metallothionein up-regulation in rat liver and kidney

    DEFF Research Database (Denmark)

    Jakobsen, Stig Storgaard; Danscher, Gorm; Stoltenberg, Meredin

    2007-01-01

    Cobalt-chromium-molybdenum (CoCrMo) metal-on-metal hip prosthesis has had a revival due to their excellent wear properties. However, particulate wear debris and metal ions liberated from the CoCrMo alloys might cause carcinogenicity, hypersensitivity, local and general tissue toxicity, genotoxici...... and that they accumulate in liver and kidney tissue. That the liberated metal ions affect the tissues is supported by an up-regulation of the detoxifying/pacifying metalloprotein I/II in the liver. Udgivelsesdato: 2007-Dec...

  11. Effect of autoclave heat treatments on the mechanical properties of the prealloyed powder cobalt-base alloy HS-31

    Science.gov (United States)

    Freche, J. C.; Ashbrook, R. L.

    1973-01-01

    The cobalt-base alloy HS-31 was atomized into powder and then consolidated by extrusion or by hot isostatic pressing (HIP) in an autoclave over a range of temperatures spanning the solidus, approximately 2340 F. Extrusions were subsequently autoclaved at the same conditions. Extrusions autoclaved at 2420 F had a life of 300 hours at 1200 F and 30 hours at 1800 F at stresses that result in a 10-hour life with cast HS-31. Superior stress rupture lives of autoclaved material are probably related to the solidification structure at the grain boundaries as well as to the increased grain size.

  12. Integrated Computational Materials Engineering Development of Alternative Cu-Be Alloys

    Science.gov (United States)

    2012-08-01

    Structure – Property Tools Design Framework: Precipitation- strengthened Copper and Cobalt alloy NGCu-1: Design constraints and associated... superalloys ● Excellent chemical/erosion resistance Binary Co – Cr phase diagram 9 Co-Based Alloys Drivers\\Requirements Precipitation Strengthened...for Cobalt -based designs FCC matrix + L12 strengthening precipitates Risk Factor Mitigation strategy Quench suppressibility • lower solvus of L12

  13. Titanium aluminide intermetallic alloys with improved wear resistance

    Science.gov (United States)

    Qu, Jun; Lin, Hua-Tay; Blau, Peter J.; Sikka, Vinod K.

    2014-07-08

    The invention is directed to a method for producing a titanium aluminide intermetallic alloy composition having an improved wear resistance, the method comprising heating a titanium aluminide intermetallic alloy material in an oxygen-containing environment at a temperature and for a time sufficient to produce a top oxide layer and underlying oxygen-diffused layer, followed by removal of the top oxide layer such that the oxygen-diffused layer is exposed. The invention is also directed to the resulting oxygen-diffused titanium aluminide intermetallic alloy, as well as mechanical components or devices containing the improved alloy composition.

  14. Effect of recasting on the elastic modulus of metal-ceramic systems from nickel-chromium and cobalt-chromium alloys

    Directory of Open Access Journals (Sweden)

    Mirković Nemanja

    2007-01-01

    Full Text Available Background/Aim. Elastic modulus of metal-ceramic systems determines their flexural strength and prevents damages on ceramics during mastication. Recycling of basic alloys is often a clinical practice, despite the possible effects on the quality of the future metal-ceramic dentures. This research was done to establish recasting effects of nickel-chromium and cobalt-chromium alloys on the elastic modulus of metalceramic systems in making fixed partial dentures. Methods. The research was performed as an experimental study. Six metal-ceramic samples of nickel-chromium alloy (Wiron 99 and cobalt-chromium alloy (Wirobond C were made. Alloy residues were recycled through twelve casting generations with the addition of 50% of new alloy on the occasion of every recasting. Three- point bending test was used to determine elastic modulus, recommended by the standard ISO 9693:1999. Fracture load for damaging ceramic layer was recorded on the universal testing machine (Zwick, type 1464, with the speed of 0,05 mm/min. Results. The results of this research revealed significant differences between elasticity modules of metal-ceramic samples in every examined recycle generation. Recasting had negative effect on the elastic modulus of the examined alloys. This research showed the slight linear reduction of elastic modulus up to the 6th generation of recycling. After the 6th recycling there was a sudden fall of elastic modulus. Conclusion. Recasting of nickelchromium and cobalt-chromium alloys is not recommended because of the reduced elastic modulus of these alloys. Instead of reusing previously recasted alloys, the alloy residues should be returned to the manufacturer. .

  15. Understanding the roles of the strategic element cobalt in nickel base superalloys

    Science.gov (United States)

    Stephens, J. R.; Dreshfield, R. L.

    1983-01-01

    The United States imports over 90% of its cobalt, chromium, columbium, and tantalum, all key elements in high temperature nickel base superalloys for aircraft gas turbine disks and airfoils. Research progress in understanding the roles of cobalt and some possible substitutes effects on microstructure, mechanical properties, and environmental resistance of turbine alloys is discussed.

  16. Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nikel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) seamless pipe and tube

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nikel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) seamless pipe and tube

  17. Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045 and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) plate, sheet and strip

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045 and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) plate, sheet and strip

  18. Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) rod, bar, and wire

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2011-01-01

    Standard specification for Nickel-Chromium-Iron alloys (UNS N06600, N06601, N06603, N06690, N06693, N06025, N06045, and N06696), Nickel-Chromium-Cobalt-Molybdenum alloy (UNS N06617), and Nickel-Iron-Chromium-Tungsten alloy (UNS N06674) rod, bar, and wire

  19. The effect of stainless steel, cobalt-chromium, titanium alloy, and titanium on the respiratory burst activity of human polymorphonuclear leukocytes.

    Science.gov (United States)

    Pascual, A; Tsukayama, D T; Wicklund, B H; Bechtold, J E; Merritt, K; Peterson, P K; Gustilo, R B

    1992-07-01

    Although infection is a serious complication associated with the use of orthopedic prosthetic implants, the impact of the metal used in these devices on host defense is poorly understood. The authors investigated the effect of stainless steel, titanium, titanium alloy, and cobalt-chromium alloy on the respiratory burst of polymorphonuclear leukocytes (PMN), a vital component of bactericidal activity. In the presence of stainless steel powder or supernatants obtained from the incubation of stainless steel in buffer, superoxide production by PMN was significantly impaired. Titanium, titanium alloy, and cobalt-chrome alloy had no significant effect on superoxide production. Nickel and chromium, the only metal ions detectable in the stainless steel supernatant, did not impair superoxide production when tested at concentrations similar to those found in the supernatant. Inhibition of PMN superoxide production may play a role in the establishment and persistence of stainless steel device-related infections.

  20. Electrical resistivity of liquid binary and ternary alloys

    International Nuclear Information System (INIS)

    Ornat, M.; Paja, A.

    2011-01-01

    New method of calculation of the electrical resistivity of liquid and amorphous alloys is presented. The method is based on the Morgan-Howson-Saub (MHS) model but the pseudopotentials are replaced by the scattering matrix operators. The Fermi energy is properly determined by the accurate values of the phase shifts. The model depends on a very small number of universal parameters and gives stable results. The calculated values of the resistivity agree well with available experimental data for a substantial number of binary alloys. Moreover, the results for some ternary alloys were also obtained. (orig.)

  1. The effect of remelting various combinations of new and used cobalt-chromium alloy on the mechanical properties and microstructure of the alloy.

    Science.gov (United States)

    Gupta, Sharad; Mehta, Aruna S

    2012-01-01

    Remelting previously cast base metal alloy can adversely affect the mechanical properties of the alloy and necessitates addition of new alloy. To study the effect of remelting different combinations of new and used cobalt-chromium (Co-Cr) alloy on its mechanical properties and microstructure. Using induction casting, 24 tensile test specimens were prepared for eight different combinations of new and used Co-Cr alloy. The test specimens were assessed for yield strength and percentage elongation. Microhardness was evaluated using Vickers's hardness tester. The tensile testing was carried out on a 50 kN servo-hydraulic universal testing machine. Microstructure analysis was done using an optical photomicroscope on the fractured samples after acid etching. The mean values (±standard deviation) and coefficient of variation were calculated. Student's 't' test was used for statistical analysis. Statistical significance was assumed at P=.05. The mean yield strength of eight different combination groups were as follows: group A: 849 MPa, group B ₁ : 834 MPa, group B ₂ : 915 MPa, group B ₃ : 897 MPa, group C ₁ : 874 MPa, group C ₂ : 859 MPa, group D ₁ : 845 MPa, and group D ₂ : 834 MPa. The mean percentage elongation for the different groups were as follows: group A: 7%, group B ₁ : 7%, group B ₂ : 8%, group B ₃ : 7%, group C ₁ : 8%, group C ₂ : 7%, group D ₁ : 7%, and group D 2 : 8%. The mean hardness values were as follows: group A: 373 VHN, group B ₁ : 373 VHN, group B ₂ : 346 VHN, group B ₃ : 346 VHN, group C ₁ : 364 VHN, group C ₂ : 343 VHN, group D ₁ : 376 VHN, and group D ₂ : 373 VHN. Repeated remelting of base metal alloy for dental casting without addition of new alloy can affect the mechanical properties of the alloy. Microstructure analysis shows deterioration upon remelting. However, the addition of 25% and 50% (by weight) of new alloy to the remelted alloy can bring about improvement both in mechanical properties and in

  2. An investigation of force components in orthogonal cutting of medical grade cobalt-chromium alloy (ASTM F1537).

    Science.gov (United States)

    Baron, Szymon; Ahearne, Eamonn

    2017-04-01

    An ageing population, increased physical activity and obesity are identified as lifestyle changes that are contributing to the ongoing growth in the use of in-vivo prosthetics for total hip and knee arthroplasty. Cobalt-chromium-molybdenum (Co-Cr-Mo) alloys, due to their mechanical properties and excellent biocompatibility, qualify as a class of materials that meet the stringent functional requirements of these devices. To cost effectively assure the required dimensional and geometric tolerances, manufacturers rely on high-precision machining. However, a comprehensive literature review has shown that there has been limited research into the fundamental mechanisms in mechanical cutting of these alloys. This article reports on the determination of the basic cutting-force coefficients in orthogonal cutting of medical grade Co-Cr-Mo alloy ASTM F1537 over an extended range of cutting speeds ([Formula: see text]) and levels of undeformed chip thickness ([Formula: see text]). A detailed characterisation of the segmented chip morphology over this range is also reported, allowing for an estimation of the shear plane angle and, overall, providing a basis for macro-mechanic modelling of more complex cutting processes. The results are compared with a baseline medical grade titanium alloy, Ti-6Al-4V ASTM F136, and it is shown that the tangential and thrust-force components generated were, respectively, ≈35% and ≈84% higher, depending primarily on undeformed chip thickness but with some influence of the cutting speed.

  3. Influence of a tungsten metal conditioner on the adhesion and residual stress of porcelain bonded to cobalt-chromium alloy.

    Science.gov (United States)

    Ting, Stephanie; Li, Kai Chun; Waddell, J Neil; Prior, David J; Jansen van Vuuren, Ludwig; Swain, Michael V

    2014-09-01

    Cobalt-chromium (CoCr) metal ceramic restorations are known to be more susceptible to cracking and interfacial failures. This is partially related to their high potential for oxidation compared with restorations made with high noble alloys. One approach that may improve their compatibility is the use of bonding agents. The purpose of this study was to investigate the influence of a tungsten metal conditioner on the adhesion and residual stress of porcelain bonded to a cobalt-chromium alloy. Eighty-one metal-porcelain bilayered specimens were manufactured and tested with a 4-point bend for adhesion and with Vickers indentation for residual stress determination. The strain energy release rate for adhesion energy and indentation residual stress was evaluated for specimens layered with and without tungsten (W) metal conditioner. Subsequent scanning electron microscopy and energy dispersive spectrometry were performed to identify fracture behavior and chemical and phase compositions. The average strain energy release rate of the specimen group tested without the W metal conditioner was significantly higher (P<.05) (44.70 J/m(2)) than that of the group with the W metal conditioner (28.65 J/m(2)). The average residual stress of the specimen group with (0.1 MPa) and without (1.61 MPa) the W metal conditioner did not differ significantly. Scanning electron microscopy and energy dispersive spectrometry analysis enabled the modes of failure to be determined and indicated the mechanisms by which the W metal conditioner influenced the bond. The W metal conditioner used in this study significantly lowered the strain energy release rate of the porcelain-cobalt-chromium interface and did not have a significant influence on the residual stress state of the porcelain. Copyright © 2014 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  4. Corrosion resistant Ti alloy for sulphuric acid medium: Suitability of Ti-Mo alloys

    Energy Technology Data Exchange (ETDEWEB)

    Balusamy, T.; Jamesh, M.; Kumar, Satendra; Narayanan, T.S.N. Sankara [National Metallurgical Laboratory, Madras Centre, CSIR Complex, Taramani, Chennai 600 113 (India)

    2012-09-15

    The corrosion resistance of Ti-Mo (5, 10, 15 and 25 wt% molybdenum) alloys in 5-25% sulphuric acid was evaluated. The Ti-Mo alloys offered a better corrosion resistance than commercially pure titanium (CP-Ti). The higher impedance values, higher phase angle maximum, ability to reach the phase angle maximum at relatively lower frequencies, ability to exhibit a constant phase angle maximum over a wider range of frequencies, higher phase angle values at 0.01 Hz, have confirmed the formation of a stable passive oxide film on Ti-Mo alloys. The study recommends the use of Ti-Mo alloys, particularly Ti-25Mo alloy, as a suitable material of construction for sulphuric acid medium. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  5. Corrosion-Resistant High-Entropy Alloys: A Review

    Directory of Open Access Journals (Sweden)

    Yunzhu Shi

    2017-02-01

    Full Text Available Corrosion destroys more than three percent of the world’s gross domestic product. Therefore, the design of highly corrosion-resistant materials is urgently needed. By breaking the classical alloy-design philosophy, high-entropy alloys (HEAs possess unique microstructures, which are solid solutions with random arrangements of multiple elements. The particular locally-disordered chemical environment is expected to lead to unique corrosion-resistant properties. In this review, the studies of the corrosion-resistant HEAs during the last decade are summarized. The corrosion-resistant properties of HEAs in various aqueous environments and the corrosion behavior of HEA coatings are presented. The effects of environments, alloying elements, and processing methods on the corrosion resistance are analyzed in detail. Furthermore, the possible directions of future work regarding the corrosion behavior of HEAs are suggested.

  6. Correlation between crystallographic texture, microstructure and magnetic properties of pulse electrodeposited nanocrystalline Nickel–Cobalt alloys

    Energy Technology Data Exchange (ETDEWEB)

    Sharma, Amit; Chhangani, Sumit; Madhavan, R.; Suwas, Satyam, E-mail: satyamsuwas@materials.iisc.ernet.in

    2017-07-15

    Highlights: • Nano-crystalline Ni–Co materials with varying composition has been deposited by pulse electrodeposition. • Overall weakening of <1 1 1> texture and strengthening of <2 0 0> fibre texture is observed with increasing cobalt content. • Higher thermal stability of Ni–70Co is interpreted in terms of low mobility twins and texture. • A clear transition from soft to hard magnetic character is observed with an increase cobalt content. - Abstract: This paper reports the evolution of microstructure and texture in Nickel–Cobalt electrodeposits fabricated by pulse electrodeposition (PED) technique and the correlation of these attributes with the magnetic properties. The structural and microstructural investigation using X-ray diffraction and transmission electron microscopic studies indicate the presence of nanocrystalline grains and nano-twins in the electrodeposits. Convoluted Multiple Whole profile fitting reveals an increase in dislocation density and twin density with increasing cobalt content in the as-deposited samples. Strengthening of <1 1 1> fibre texture and weakening of <2 0 0> fibre texture with increasing cobalt concentration has been observed with X-ray texture analysis. A corresponding significant increase in the saturation magnetization and coercivity observed with increasing cobalt content. A significant improvement in the soft magnetic character in the electrodeposits in terms of increase in saturation magnetization and decrease in coercivity has been observed with thermal annealing.

  7. Vanadium alloys with improved resistance to helium embrittlement

    Energy Technology Data Exchange (ETDEWEB)

    Braski, D.N.

    1990-01-01

    A series of experimental vanadium alloys have been designed with small MC-type carbides in their microstructures to trap helium produced during neutron irradiation, thereby reducing helium embrittlement. The tensile properties and fabricability of the alloys were strongly influenced by the amounts of MC-forming-elements, especially carbon. Alloys with 0.05 and 0.10 wt % carbon exhibited slightly lower yield strengths at 420 to 600{degree}C than vanadium alloys such as V-5Cr-5Ti, Vanstar-7, V-3Ti-1Si, and V-15Cr-5Ti. However, this characteristic may actually be an asset from the standpoint of resistance to irradiation hardening. After implantation with 300 appm {sup 3}He, both the V-Ti-C and V-Ti-Zr-C alloys exhibited less ductility losses at 600{degree}C than the other vanadium alloys tested under comparable conditions. Examination of the experimental alloy microstructures by AEM showed that the small MC-type carbides did, in fact, trap helium and that they were responsible for the increased resistance to helium embrittlement of these alloys. 16 refs., 12 figs., 2 tabs.

  8. Laser Surface Alloying of Aluminum for Improving Acid Corrosion Resistance

    Science.gov (United States)

    Jiru, Woldetinsay Gutu; Sankar, Mamilla Ravi; Dixit, Uday Shanker

    2018-04-01

    In the present study, laser surface alloying of aluminum with magnesium, manganese, titanium and zinc, respectively, was carried out to improve acid corrosion resistance. Laser surface alloying was conducted using 1600 and 1800 W power source using CO2 laser. Acid corrosion resistance was tested by dipping the samples in a solution of 2.5% H2SO4 for 200 h. The weight loss due to acid corrosion was reduced by 55% for AlTi, 41% for AlMg alloy, 36% for AlZn and 22% for AlMn alloy. Laser surface alloyed samples offered greater corrosion resistance than the aluminum substrate. It was observed that localized pitting corrosion was the major factor to damage the surface when exposed for a long time. The hardness after laser surface alloying was increased by a factor of 8.7, 3.4, 2.7 and 2 by alloying with Mn, Mg, Ti and Zn, respectively. After corrosion test, hardness was reduced by 51% for AlTi sample, 40% for AlMg sample, 41.4% for AlMn sample and 33% for AlZn sample.

  9. Influence of impurities and ion surface alloying on the corrosion resistance of E110 alloy

    International Nuclear Information System (INIS)

    Kalin, B. A.; Volkov, N. V.; Valikov, R. A.; Novikov, V. V.; Markelov, V. A.; Pimenov, Yu. V.

    2013-01-01

    The corrosion resistance of zirconium alloys depends on their structural-phase state, the type of core coolant and operating factors. The formation of a protective oxide film on the zirconium alloys is sensitive to the content of impurity atoms present in the charge base of alloys and accumulating in them in the manufacture of products. The impurity composition of the initial zirconium is determined by the method of its manufacture and generally remains unchanged in the products, deter-mining their properties, including their corrosion resistance. An increased content of impurities (C, N, Al, Mo, Fe) both individually and in their combination negatively affects the corrosion resistance of zirconium and its alloys. One of the potentially effective methods to increase the protective properties of oxide films on zirconium alloys is a surface alloying using the regime of mixing the atoms of a film, preliminarily coated on the surface, and the atoms of a target. This method makes it possible to form a given structural-phase state in the thin surface layer with unique physicochemical properties and thus to in-crease the corrosion resistance and wear resistance of fuel claddings. In this context, the object of investigation was samples of cladding tubes from alloy E110 with various content of impurity elements (nitrogen, aluminum, and carbon) with the aim to reduce the negative influence of impurities on the corrosion resistance by changing the structural-phase state of the surface layer of fuel claddings and fuel assembly components with alloying in the regime of ion mixing of atoms

  10. Towards a Cycle without Loss. Cobalt in the Aircraft Industry,

    Science.gov (United States)

    COBALT , *AIRCRAFT INDUSTRY, *STRATEGIC MATERIALS, *MANUFACTURING, CYCLES, SUPERALLOYS , HIGH STRENGTH ALLOYS, STEEL, TOOL STEEL, ALLOYS, QUANTITATIVE ANALYSIS, MATERIALS RECOVERY, RATES, ALLOYS, RECYCLED MATERIALS, LOSSES, SYMPOSIA

  11. Influence of cobalt content on the structure and hard magnetic properties of nanocomposite (Fe,Co)-Pt-B alloys

    Energy Technology Data Exchange (ETDEWEB)

    Grabias, A., E-mail: agnieszka.grabias@itme.edu.pl [Institute of Electronic Materials Technology, Wólczyńska 133, 01-919 Warsaw (Poland); Kopcewicz, M. [Institute of Electronic Materials Technology, Wólczyńska 133, 01-919 Warsaw (Poland); Latuch, J.; Oleszak, D. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw (Poland); Pękała, M. [Department of Chemistry, University of Warsaw, Al. Żwirki i Wigury 101, 02-089 Warsaw (Poland); Kowalczyk, M. [Faculty of Materials Science and Engineering, Warsaw University of Technology, Wołoska 141, 02-507 Warsaw (Poland)

    2017-07-15

    Highlights: • Nanocomposite alloys were formed by annealing of the rapidly quenched alloys. • Magnetically hard L1{sub 0} (Fe,Co)Pt and soft (Fe,Co){sub 2}B or (Fe,Co)B were formed. • Mössbauer spectra revealed Co substitution for Fe in L1{sub 0} FePt, FeB and Fe{sub 2}B phases. • Annealed alloys exhibit hard magnetic properties which depend on phase compositions. • Co addition was found to decrease the magnetization and the energy product. - Abstract: The influence of Co content on the structural and hard magnetic properties of two sets of nanocrystalline Fe{sub 52−x}Co{sub x}Pt{sub 28}B{sub 20} (x = 0–26) and Fe{sub 60−y}Co{sub y}Pt{sub 25}B{sub 15} (y = 0–40) alloys was studied. The alloys were prepared as ribbons by the rapid quenching technique. The nanocomposite structure in the alloys was obtained by annealing at 840–880 K for 30 min. Structural characterization of the samples was performed using the Mössbauer spectroscopy and X-ray diffraction. Magnetic properties of the samples were studied by the measurements of the hysteresis loops and of the magnetization at increasing temperatures. An amorphous phase prevailed in the as-quenched Fe{sub 52−x}Co{sub x}Pt{sub 28}B{sub 20} alloys while a disordered solid solution of fcc-(Fe,Co)Pt was a dominating phase in the Fe{sub 60−y}Co{sub y}Pt{sub 25}B{sub 15} ribbons. Differential scanning calorimetry measurements revealed one or two exothermic peaks at temperatures up to 993 K, depending on the composition of the alloys. Thermal treatment of the samples led to the formation of the magnetically hard ordered L1{sub 0} tetragonal (Fe,Co)Pt nanocrystallites and magnetically softer phases of (Fe,Co)B (for Fe{sub 52−x}Co{sub x}Pt{sub 28}B{sub 20}) or (Fe,Co){sub 2}B (for Fe{sub 60−y}Co{sub y}Pt{sub 25}B{sub 15}). Detailed Mössbauer spectroscopy studies revealed that cobalt substituted for iron in both the L1{sub 0} phase and in iron borides. The nanocomposite Fe{sub 60−y}Co{sub y

  12. Effect of annealing procedure on the bonding of ceramic to cobalt-chromium alloys fabricated by rapid prototyping.

    Science.gov (United States)

    Tulga, Ayca

    2017-08-22

    An annealing procedure is a heat treatment process to improve the mechanical properties of cobalt-chromium (Co-Cr) alloys. However, information is lacking about the effect of the annealing process on the bonding ability of ceramic to Co-Cr alloys fabricated by rapid prototyping. The purpose of this in vitro study was to evaluate the effects of the fabrication techniques and the annealing procedure on the shear bond strength of ceramic to Co-Cr alloys fabricated by different techniques. Ninety-six cylindrical specimens (10-mm diameter, 10-mm height) made of Co-Cr alloy were prepared by casting (C), milling (M), direct process powder-bed (LaserCUSING) with and without annealing (CL+, CL), and direct metal laser sintering (DMLS) with annealing (EL+) and without annealing (EL). After the application of ceramic to the metal specimens, the metal-ceramic bond strength was assessed using a shear force test at a crosshead speed of 0.5 mm/min. Shear bond strength values were statistically analyzed by 1-way ANOVA and Tukey multiple comparison tests (α=.05). Although statistically significant differences were found among the 3 groups (M, 29.87 ±2.06; EL, 38.92 ±2.04; and CL+, 40.93 ±2.21; P=.002), no significant differences were found among the others (P>.05). The debonding surfaces of all specimens exhibited mixed failure mode. These results showed that the direct process powder-bed method is promising in terms of metal-ceramic bonding ability. The manufacturing technique of Co-Cr alloys and the annealing process influence metal-ceramic bonding. Copyright © 2017 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  13. Wear resistance of alloy вт-22 with non-ferrous alloys at reverse

    Directory of Open Access Journals (Sweden)

    А.М. Хімко

    2010-01-01

    Full Text Available  The article presents the results of tests of non hardened titanium alloy ВТ-22 with aviation non-ferrous alloys in reverse sliding friction. The main objective of the work is the selection of the optimum combination of materials depending on changes in loading conditions. Study of alloy ВТ-22 wear resistance was carried out in pairs with БрОФ-10-1, БрБ2, БрАЖ-9-4, ВТ-22, МЛ5, Д16Т, 7Х21ГАН5Ш and 95Х18Ш. The dependencies of the materials wear at pressures 10, 20 and 30 Mpa we determined. The linear nature of titanium alloy wear curves indicates that the change in the wear mechanism occurs gradually. The histograms of non-ferrous materials wear and the total wear of the friction pair are presented. It is established that the bronze БрАЖ-9-4 is the most preferable material for contact with non hardened titanium alloy ВТ-22, the least wear among the tested materials. The established coefficients of the titanium alloy ВТ-22 friction in pair with aviation structural non-ferrous alloys are presented. The results of research will be relevant for the engineering industry, where non hardened titanium alloy ВТ-22 in pair with non-ferrous alloys is applied.

  14. Nickel and cobalt release from metal alloys of tools--a current analysis in Germany.

    Science.gov (United States)

    Kickinger-Lörsch, Anja; Bruckner, Thomas; Mahler, Vera

    2015-11-01

    The former 'EU Nickel Directive' and, since 2009, the REACH Regulation (item 27 of Annex XVII) do not include all metallic objects. The nickel content of tools is not regulated by the REACH Regulation, even if they may come into in prolonged contact with the skin. Tools might be possible sources of nickel and cobalt sensitization, and may contribute to elicitation and maintenance of hand eczema. To perform a current analysis of the frequency of nickel or cobalt release from new handheld tools purchased in Germany. Six hundred unused handheld tools from the German market were investigated with the dimethylglyoxime test for nickel release and with disodium-1-nitroso-2-naphthol-3,6-disulfonate solution for cobalt release. Nickel release was detected in 195 of 600 (32.5%) items, and cobalt in only six (1%) of them. Positive nickel results were nearly twice as frequent in tools 'made in Germany' than in tools without a mark of origin. Tools made in other European countries did not release nickel. Cobalt release was only found in pliers and a saw. A correlation was found between price level and nickel release. Among toolkits, 34.2% were inhomogeneous concerning nickel release. The German market currently provides a large number of handheld tools that release nickel, especially tools 'made in Germany'. For consumer protection, it seems appropriate to include handheld tools in the REACH Regulation on nickel. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  15. Microstructural characteristics of the nickel-based alloy IN738LC and the cobalt-based alloy Mar-M509 produced by selective laser melting

    Energy Technology Data Exchange (ETDEWEB)

    Cloots, Michael, E-mail: cloots@inspire.ethz.ch [Inspire AG, ETH Zurich, Lerchenfeldstrasse 5, 9014 St. Gallen (Switzerland); Kunze, Karsten [Scientific Center of Optical and Electron Microscopy, ETH Zurich, Auguste-Piccard-Hof 1, 8093 Zurich (Switzerland); Uggowitzer, Peter J. [Laboratory of Metal Physics and Technology, ETH Zurich, Vladimir-Prelog-Weg 4, 8093 Zurich (Switzerland); Wegener, Konrad [Institute of Machine Tools and Manufacturing (IWF), ETH Zurich, Leonhardstrasse 21, 8092 Zurich (Switzerland)

    2016-03-21

    This study investigates selective laser melting (SLM) of the nickel based superalloy IN738LC and the cobalt based alloy Mar-M509, and identifies the influence of process and material parameters on the resulting microstructure. Comprehensive microstructural characterization was performed using electron backscattered diffraction analysis. Significant differences between IN738LC and Mar-M509 were observed with respect to grain size, grain shape and texture sharpness. Alloy IN738LC exhibits coarse and elongated grains with a sharp texture and thus a pronounced mechanical anisotropy. Alloy Mar-M509 shows smaller grains with only moderate structural and mechanical anisotropy. The different microstructural and mechanical characteristics are attributed to the different recovery and recrystallization behavior of IN738LC and Mar-M509. The high stacking fault energy (SFE) of IN738LC results in pronounced recovery of lattice defects without affecting the basic grain structure, whereas the low SFE in Mar-M509 favors recrystallization with the effect of significant grain refinement and weakening of the solidification texture. The effect of microstructure and the structural anisotropy on the orientation-dependent values of the Young’s modulus and the mechanical properties are further discussed.

  16. The response of cobalt-free Udimet 700 type alloy to modified heat treatments

    Science.gov (United States)

    Harf, F. H.

    1986-01-01

    A superalloy based on Udimet 700, in which all of the cobalt was replaced by nickel, was prepared from hot isostatically pressed prealloyed powders. This material was given various heat treatments consisting of partial solutioning and aging in a sequence of four different temperatures. Comparisons were made of microstructures and mechanical properties. Best results were obtained by partially solutioning at 1145 deg C and aging through a sequence of 870, 1030, 650 and 760 deg C. This heat treatment also provided significantly improved properties for wrought material of the same composition. The results suggest that cobalt free Udimet 700 should be considered as a substitute for Udimet 700 with the standard 17 percent cobalt content.

  17. Electrical resistivity of V-Cr-Ti alloys

    International Nuclear Information System (INIS)

    Zinkle, S.J.; Gubbi, A.N.; Eatherly, W.S.

    1997-01-01

    Room temperature electrical resistivity measurements have been performed on vanadium alloys containing 3-6%Cr and 3-6%Ti in order to evaluate the microstructural stability of these alloys. A nonlinear dependence on Cr and Ti concentration was observed, which suggests that either short range ordering or solute precipitation (perhaps in concert with interstitial solute clustering) has occurred in V-6Cr-6Ti

  18. Creep-fatigue of low cobalt superalloys

    Science.gov (United States)

    Halford, G. R.

    1982-01-01

    Testing for the low cycle fatigue and creep fatigue resistance of superalloys containing reduced amounts of cobalt is described. The test matrix employed involves a single high temperature appropriate for each alloy. A single total strain range, again appropriate to each alloy, is used in conducting strain controlled, low cycle, creep fatigue tests. The total strain range is based upon the level of straining that results in about 10,000 cycles to failure in a high frequency (0.5 Hz) continuous strain-cycling fatigue test. No creep is expected to occur in such a test. To bracket the influence of creep on the cyclic strain resistance, strain hold time tests with ore minute hold periods are introduced. One test per composition is conducted with the hold period in tension only, one in compression only, and one in both tension and compression. The test temperatures, alloys, and their cobalt compositions that are under study are given.

  19. Macrophages detoxify the genotoxic and cytotoxic effects of surgical cobalt chrome alloy particles but not quartz particles on human cells in vitro.

    Science.gov (United States)

    Papageorgiou, I; Shadrick, V; Davis, S; Hails, L; Schins, R; Newson, R; Fisher, J; Ingham, E; Case, C P

    2008-08-25

    Particles of surgical cobalt chrome alloy are cytotoxic and genotoxic to human fibroblasts in vitro. In vivo orthopaedic patients are exposed to cobalt chrome particles as a result of wear of a joint replacement. Many of the wear debris particles that are produced are phagocytosed by macrophages that accumulate at the site of the worn implant and are disseminated to local and distant lymph nodes the liver and the spleen. In this study we have tested whether this process of phagocytosis could have altered the cytotoxic and genotoxic properties of the cobalt chrome particles. Quartz particles have been investigated as a control. Micron-sized particles of cobalt chrome alloy were internalised by either white cells of peripheral blood or by THP-1 monocytes for 1 week and 1 day, respectively. The particles were then extracted and presented at different doses to fibroblasts for 1 day. There was a reduction of the cytotoxicity and genotoxicity of the cobalt chrome particles after phagocytosis by white cells or THP-1 cells. Cobalt chrome particles that were internalised by fibroblasts also showed a reduction of their cytotoxicity but not their genotoxicity. In contrast the cytotoxicity and genotoxicity of quartz particles was increased after internalisation by THP-1 cells. The surface morphology of the cobalt chrome particles but not the quartz particles was changed after phagocytosis by THP-1 cells. This study suggests that the genotoxic and cytotoxic properties of particles that fall within the size range for phagocytosis may be highly complex in vivo and depend on the combination of material type and previous phagocytosis. These results may have relevance for particle exposure from orthopaedic implants and from environmental or industrial pollution.

  20. The effect of UV-photofunctionalization on the time-related bioactivity of titanium and chromium-cobalt alloys.

    Science.gov (United States)

    Att, Wael; Hori, Norio; Iwasa, Fuminori; Yamada, Masahiro; Ueno, Takeshi; Ogawa, Takahiro

    2009-09-01

    This study examined the possible changes in the bioactivity of titanium surfaces during their aging and investigated the effect of ultraviolet (UV) light treatment during the age-related change of titanium bioactivity. Rat bone marrow-derived osteoblastic cells were cultured on new titanium disks (immediately after either acid-etching, machining, or sandblasting), 4-week-old disks (stored after processing for 4 weeks in dark ambient conditions), and 4-week-old disks treated with UVA (peak wavelength of 365 nm) or UVC (peak wavelength of 250 nm). During incubation for 24 h, only 50% of the cells were attached to the 4-week-old surfaces as compared to the new surface. UVC treatment of the aged surface increased its cell attachment capacity to a level 50% higher than the new surfaces, whereas UVA treatment had no effect. Proliferation, alkaline phosphatase activity, and mineralization of cells were substantially lower on the 4-week-old surfaces than on the new surfaces, while they were higher on the UVC-treated 4-week-old surfaces as compared to the new surfaces. The age-related impaired bioactivity was found on all titanium topographies as well as on a chromium-cobalt alloy, and was associated with an increased percentage of surface carbon. Although both UVA and UVC treatment converted the 4-week-old titanium surfaces from hydrophobic to superhydrophilic, only UVC treatment effectively reduced the surface carbon to a level equivalent to the new surface. Thus, this study uncovered a time-dependent biological degradation of titanium and chromium-cobalt alloy, and its restoration enabled by UVC phototreatment, which surmounts the innate bioactivity of new surfaces, which is more closely linked to hydrocarbon removal than the induced superhydrophilicity.

  1. Ferritic Alloys with Extreme Creep Resistance via Coherent Hierarchical Precipitates

    Science.gov (United States)

    Song, Gian; Sun, Zhiqian; Li, Lin; Xu, Xiandong; Rawlings, Michael; Liebscher, Christian H.; Clausen, Bjørn; Poplawsky, Jonathan; Leonard, Donovan N.; Huang, Shenyan; Teng, Zhenke; Liu, Chain T.; Asta, Mark D.; Gao, Yanfei; Dunand, David C.; Ghosh, Gautam; Chen, Mingwei; Fine, Morris E.; Liaw, Peter K.

    2015-11-01

    There have been numerous efforts to develop creep-resistant materials strengthened by incoherent particles at high temperatures and stresses in response to future energy needs for steam turbines in thermal-power plants. However, the microstructural instability of the incoherent-particle-strengthened ferritic steels limits their application to temperatures below 900 K. Here, we report a novel ferritic alloy with the excellent creep resistance enhanced by coherent hierarchical precipitates, using the integrated experimental (transmission-electron microscopy/scanning-transmission-electron microscopy, in-situ neutron diffraction, and atom-probe tomography) and theoretical (crystal-plasticity finite-element modeling) approaches. This alloy is strengthened by nano-scaled L21-Ni2TiAl (Heusler phase)-based precipitates, which themselves contain coherent nano-scaled B2 zones. These coherent hierarchical precipitates are uniformly distributed within the Fe matrix. Our hierarchical structure material exhibits the superior creep resistance at 973 K in terms of the minimal creep rate, which is four orders of magnitude lower than that of conventional ferritic steels. These results provide a new alloy-design strategy using the novel concept of hierarchical precipitates and the fundamental science for developing creep-resistant ferritic alloys. The present research will broaden the applications of ferritic alloys to higher temperatures.

  2. BMP-7 ameliorates cobalt alloy particle-induced inflammation by suppressing Th17 responses.

    Science.gov (United States)

    Chen, Fengrong; Chen, Ruisong; Liu, Haoyuan; Sun, Rupeng; Huang, Jianming; Huang, Zheyuan; Jian, Guojian

    2017-10-01

    Metal wear debris has been shown to activate an aseptic osteolytic process that causes failure in total joint arthroplasty (TJA). This osteolysis is characterized by a proinflammatory, self-propagating immune response involving primarily macrophages, dendritic cells, and activated osteoclasts, as well as T cells and B cells. The human bone morphogenic protein (BMP)-7, on the other hand, was shown to promote osteoblast survival, and reversed the downregulation of anabolic Smad proteins and Runx2 following cobalt injury. Therefore, we investigated the effect and mechanism of BMP-7 on the proinflammatory immune responses in osteoarthritis patients with previous TJA. Cobalt-treated monocytes/macrophages presented significantly elevated levels of interleukin 6 (IL-6) and tumor necrosis factor (TNF), both of which were suppressed by the addition of exogenous BMP-7. In patients with TJA, the serum BMP-7 level was inversely associated with the level of IL-6 and TNF secreted by monocytes/macrophages. Cobalt-treated monocytes/macrophages effectively supported Th17 inflammation, by an IL-6-dependent but not TNF-dependent mechanism. BMP-7, however, significantly suppressed cobalt-induced Th17 inflammation. In patients with TJA, the risk of osteolysis development was positively associated with the frequency of Th17 cells and negatively associated with the level of BMP-7. Together, these results demonstrated that BMP-7 could serve as a therapeutic agent in treating patients with metal wear debris-induced inflammation. © 2017 APMIS. Published by John Wiley & Sons Ltd.

  3. Corrosion resistance of tantalum base alloys

    International Nuclear Information System (INIS)

    Gypen, L.A.; Brabers, M.; Deruyttre, A.

    1984-01-01

    The corrosion behaviour of substitutional Ta-Mo, Ta-W, Ta-Nb, Ta-Hf, Ta-Zr, Ta-Re, Ta-Ni, Ta-V, Ta-W-Mo, Ta-W-Nb, Ta-W-Hf and Ta-W-Re alloys has been investigated in various corrosive media, i.e. (1) concentrated sulfuric acid at 250 0 C and 200 0 C, (2) boiling hydrochloric acid of azeotropic composition, (3) concentrated hydrochloric acid at 150 0 C under pressure, (4) HF-Containing solutions and (5) 0.5% H 2 SO 4 at room temperature (anodisation). In highly corrosive media such as concentrated H 2 SO 4 at 250 0 C and concentrated HCl at 150 0 C tantalum is hydrogen embrittled, probably by stress induced precipitation of β-hydride. Both corrosion rate and hydrogen embrittlement in concentrated H 2 SO 4 at 250 0 C are strongly influenced by alloying elements. Small alloying additions of either Mo or Re decrease the corrosion rate and the hydrogen embrittlement, while Hf has the opposite effect. Hydrogen embrittlement in concentrated H 2 SO 4 at 250 0 C is completely eliminated by alloying Ta with 1 to 3 at % Mo (0.5 to 1.5 wt % Mo). These results can be explained in terms of oxygen deficiency of the Ta 2 O 5 film and the electronic structure of these alloys. (orig.) [de

  4. Comparison and evaluation of marginal and internal gaps in cobalt-chromium alloy copings fabricated using subtractive and additive manufacturing.

    Science.gov (United States)

    Kim, Dong-Yeon; Kim, Ji-Hwan; Kim, Hae-Young; Kim, Woong-Chul

    2018-01-01

    To evaluate the marginal and internal gaps of cobalt-chromium (Co-Cr) alloy copings fabricated using subtractive and additive manufacturing. A study model of an abutment tooth 46 was prepared by a 2-step silicone impression with dental stone. Fifteen stereolithography files for Co-Cr alloy copings were compiled using a model scanner and dental CAD software. Using the lost wax (LW), wax block (WB), soft metal block (SMB), microstereolithography (μ-SLA), and selected laser melting (SLM) techniques, 15 Co-Cr alloy copings were fabricated per group. The marginal and internal gaps of these Co-Cr alloy copings were measured using a digital microscope (160×), and the data obtained were analyzed using the non-parametric Kruskal-Wallis H-test and post-hoc Mann-Whitney U-test with Bonferroni correction. The mean values of the marginal, axial wall, and occlusal gaps were 91.8, 83.4, and 163μm in the LW group; 94.2, 77.5, and 122μm in the WB group; 60.0, 79.4, and 90.8μm in the SMB group; 154, 72.4, and 258μm in the μ-SLA group; and 239, 73.6, and 384μm in the SLM group, respectively. The differences in the marginal and occlusal gaps between the 5 groups were statistically significant (P<.05). The marginal gaps of the LW, WB, and SMB groups were within the clinically acceptable limit, but further improvements in the μ-SLA and SLM approaches may be required prior to clinical implementation. Copyright © 2017 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  5. Experimental study of the electric resistivity in Heusler alloys

    International Nuclear Information System (INIS)

    Kunzler, J.V.

    1980-01-01

    Electrical resistivity measurements have been performed in the Cu 2 Mn (A1sub(1-x) Snsub(x)) Heusler alloys, where x = 0, 0.05, 0.10 and 0.15, in the temperature range from 4.2 to 800 0 K. Measurements have also been made on the Ni 2 MnX Heusler asloys, with X = In, Sn or Sb, in the range from 4.2 to 300 0 K. The experimental curves clearly show the importance of the ferromagnetic character for the alloys resistivity. The results obtained for the copper alloys, as well as for the Ni 2 MnSn alloy, are in agreement with an interpretation in terms of Bloch-Gruneisen and spin-disorder models, and fail to provide evidences of s-d scattering for the conduction electrons. This is not the case for the Ni 2 MnIn and Ni 2 MnSb alloys, in which the presence of (s-d) interband electronic scattering process, via phonon, was detected. Specially for the two last alloys specific heat and electronic photo-emissivity experiments are suggested. (Author) [pt

  6. Reliability of copper based alloys for electric resistance spot welding

    International Nuclear Information System (INIS)

    Jovanovicj, M.; Mihajlovicj, A.; Sherbedzhija, B.

    1977-01-01

    Durability of copper based alloys (B-5 and B-6) for electric resistance spot-welding was examined. The total amount of Be, Ni and Zr was up to 2 and 1 wt.% respectively. Good durability and satisfactory quality of welded spots were obtained in previous laboratory experiments carried out on the fixed spot-welding machine of an industrial type (only B-5 alloy was examined). Electrodes made of both B-5 and B-6 alloy were tested on spot-welding grips and fixed spot-welding machines in Tvornica automobila Sarajevo (TAS). The obtained results suggest that the durability of electrodes made of B-5 and B-6 alloys is more than twice better than of that used in TAS

  7. Effect of Bi on the corrosion resistance of zirconium alloys

    International Nuclear Information System (INIS)

    Yao Meiyi; Zhou Bangxin; Li Qiang; Zhang Weipeng; Zhu Li; Zou Linghong; Zhang Jinlong; Peng Jianchao

    2014-01-01

    In order to investigate systematically the effect of Bi addition on the corrosion resistance of zirconium alloys, different zirconium-based alloys, including Zr-4 (Zr-l.5Sn-0.2Fe-0.1Cr), S5 (Zr-0.8Sn-0.35Nb-0.4Fe-0.1Cr), T5 (Zr-0.7Sn-l.0Nb-0.3Fe-0.1Cr) and Zr-1Nb, were adopted to prepare the zirconium alloys containing Bi of 0∼0.5% in mass fraction. These alloys were denoted as Zr-4 + xBi, S5 + xBi, T5 + xBi and Zr-1Nb + xBi, respectively. The corrosion behavior of these specimens was investigated by autoclave testing in lithiated water with 0.01 M LiOH or deionized water at 360 ℃/18.6 MPa and in superheated steam at 400 ℃/10.3 MPa. The microstructure of the alloys was examined by TEM and the second phase particles (SPPs) were analyzed by EDS. Microstructure observation shows that the addition of Bi promotes the precipitation of Sn as second phase particles (SPPs) because Sn is in solid solution in α-Zr matrix in Zr-4, S5 and T5 alloys. The concentration of Bi dissolved in α-Zr matrix increase with the increase of Nb in the alloys, and the excess Bi precipitates as Bi-containing SPPs. The corrosion results show that the effect of Bi addition on the corrosion behavior of different zirconium-based alloys is very complicated, depending on their compositions and corrosion conditions. In the case of higher Bi concentration in α-Zr, the zirconium alloys exhibit better corrosion resistance. However, in the case of precipitation of Bi-containing SPPs, the corrosion resistance gets worse. This indicates that the solid solution of Bi in α-Zr matrix can improve the corrosion resistance, while the precipitation of the Bi-containing SPPs is harmful to the corrosion resistance. (authors)

  8. Metallurgical characterization of new palladium-containing cobalt chromium and nickel chromium alloys

    Science.gov (United States)

    Puri, Raghav

    Recently introduced to the market has been an entirely new subclass of casting alloy composition whereby palladium (˜25 wt%) is added to traditional base metal alloys such as CoCr and NiCr. Objectives. The purpose of this study was to evaluate the microstructure and Vickers hardness of two new CoPdCr and one new NiPdCr alloy and compare them to traditional CoCr and NiCr alloys. Methods. The casting alloys investigated were: CoPdCr-A (Noble Crown NF, The Argen Corporation), CoPdCr-I (Callisto CP+, Ivoclar Vivadent), NiPdCr (Noble Crown, Argen), CoCr (Argeloy N.P. Special, Argen), and NiCr (Argeloy N.P. Star, Argen). As-cast cylindrical alloy specimens were mounted in epoxy resin and prepared with standard metallographic procedures, i.e. grinding with successive grades of SiC paper and polishing with alumina suspensions. The alloys were examined with an optical microscope, SEM/EPMA, and XRD to gain insight into their microstructure, composition, and crystal structure. Vickers hardness (VHN) was measured and statistically analyzed by one way ANOVA and Tukey's HSD test (alpha=0.05). Results. Optical microscopy showed a dendritic microstructure for all alloys. The Pd-containing alloys appear to possess a more complex microstructure. SEM/EPMA showed Cr to be rather uniformly distributed in the matrix with palladium tending to be segregated apart from Mo and Ni or Co. Areas of different composition may explain the poor electrochemical results noted in previous studies. XRD suggested the main phase in the Ni-containing solutions was a face centered cubic Ni solid solution, whereas the CoCr exhibited a hexagonal crystal structure that was altered to face centered cubic when Pd was included in the composition. For Vickers hardness, the Co-containing alloys possessed a greater hardness than the Ni-containing alloys. However, the incorporation of Pd in CoCr and NiCr had only a slight effect on microhardness. Conclusion. Overall, the inclusion of palladium increases the

  9. Enhancement of wear and corrosion resistance of beta titanium alloy by laser gas alloying with nitrogen

    Science.gov (United States)

    Chan, Chi-Wai; Lee, Seunghwan; Smith, Graham; Sarri, Gianluca; Ng, Chi-Ho; Sharba, Ahmed; Man, Hau-Chung

    2016-03-01

    The relatively high elastic modulus coupled with the presence of toxic vanadium (V) in Ti6Al4V alloy has long been a concern in orthopaedic applications. To solve the problem, a variety of non-toxic and low modulus beta-titanium (beta-Ti) alloys have been developed. Among the beta-Ti alloy family, the quaternary Ti-Nb-Zr-Ta (TNZT) alloys have received the highest attention as a promising replacement for Ti6Al4V due to their lower elastic modulus and outstanding long term stability against corrosion in biological environments. However, the inferior wear resistance of TNZT is still a problem that must be resolved before commercialising in the orthopaedic market. In this work, a newly developed laser surface treatment technique was employed to improve the surface properties of Ti-35.3Nb-7.3Zr-5.7Ta alloy. The surface structure and composition of the laser-treated TNZT surface were examined by grazing incidence X-ray diffraction (GI-XRD) and X-ray photoelectron spectroscopy (XPS). The wear and corrosion resistance were evaluated by pin-on-plate sliding test and anodic polarisation test in Hanks' solution. The experimental results were compared with the untreated (or base) TNZT material. The research findings showed that the laser surface treatment technique reported in this work can effectively improve the wear and corrosion resistance of TNZT.

  10. Study of soft magnetic iron cobalt based alloys processed by powder injection molding

    International Nuclear Information System (INIS)

    Silva, Aline; Lozano, Jaime A.; Machado, Ricardo; Escobar, Jairo A.; Wendhausen, Paulo A.P.

    2008-01-01

    As a near net shape process, powder injection molding (PIM) opens new possibilities to process Fe-Co alloys for magnetic applications. Due to the fact that PIM does not involve plastic deformation of the material during processing, we envisioned the possibility of eliminating vanadium (V), which is generally added to Fe-Co alloys to improve the ductility in order to enable its further shaping by conventional processes such as forging and cold rolling. In our investigation we have found out two main futures related to the elimination of V, which lead to a cost-benefit gain in manufacturing small magnetic components where high-saturation induction is needed at low frequencies. Firstly, the elimination of V enables the achievement of much better magnetic properties when alloys are processed by PIM. Secondly, a lower sintering temperature can be used when the alloy is processed starting with elemental Fe and Co powders without the addition of V

  11. Treatment increases stress-corrosion resistance of aluminum alloys

    Science.gov (United States)

    Jacobs, A. J.

    1966-01-01

    Overaging during heat treatment of the aluminum alloys immediately followed by moderate plastic deformation, preferably by shock loading achieves near optimum values of both yield strength and resistance to stress corrosion. Similar results may be obtained by substituting a conventional deformation process for the shock loading step.

  12. Abrasion resistance of alloy coatings deposited by plasma spraying

    Czech Academy of Sciences Publication Activity Database

    Ctibor, Pavel; Lescoffit, A.-E.; Teboul, B.; Neufuss, Karel; Voleník, Karel

    2009-01-01

    Roč. 54, č. 2 (2009), s. 113-126 ISSN 0001-7043 R&D Projects: GA AV ČR 1QS200430560 Institutional research plan: CEZ:AV0Z20430508 Keywords : Plasma spraying * alloy coatings * slurry abrasion * hardness and microhardness Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass

  13. The Development of Corrosion Resistant Zirconium Alloy

    International Nuclear Information System (INIS)

    Abdul-Latief; Noor-Yudhi; Isfandi; Djoko-Kisworo; Pranjono

    2000-01-01

    Corrosion test of Zr alloy consisting of quenching and tempering Zry-2,Zry-4 cast, Zr-1% Nb cast, has been. conducted. In corrosion test, thechanges during β-quenching, tempering and corrosion test at varioustemperature and time in autoclave water medium, can be seen. The treatmentconsisted of heating at 1050 o C for 30 minutes, quenching in water andtempering at 200 o C, 300 o C, 400 o C, 500 o C, 600 o C as well as corrosiontests at 225 o C, 275 o C, 325 o C at 4, 8, 12 hours. Sample preparation forcorrosion test was based on ASTM G-2 procedure, which consisted of washing,rinsing, pickling (3.5 cc HF 50%; 2.9 cc HNO 3 65% and 57 cc AMB),neutralizing in 0.1 M Al(NO 3 ) 3 , 9 H 2 O and ultrasonic rinsing/washing.Measurement performed are weight gain during corrosion, hardness test andmicrostructure observation using microscope optic. The results show thatβ-quenching of Zr alloy which was followed by tempering can turn αmartensite into tempered α 1 martensit. The increase of temperingtemperature decreases the Zr alloy hardness and the lowest hardness ispossessed by Zr-1% Nb alloy. The corrosion test at 275 o C and 325 o C showsthat the weight gain depends on the tempering temperature, the temperingtemperature of 400 o C and 200 o C gives the maximum weight gain for Zry-2,Zry-4 cast, Zr-1% Nb. The largest number of hydride formed during corrosionis found in Zry-2, while the small one is in Zr-1% Nb. (author)

  14. Carbon-encapsulated nickel-cobalt alloys nanoparticles fabricated via new post-treatment strategy for hydrogen evolution in alkaline media

    Science.gov (United States)

    Guo, Hailing; Youliwasi, Nuerguli; Zhao, Lei; Chai, Yongming; Liu, Chenguang

    2018-03-01

    This paper addresses a new post-treatment strategy for the formation of carbon-encapsulated nickel-cobalt alloys nanoparticles, which is easily controlled the performance of target products via changing precursor composition, calcination conditions (e.g., temperature and atmosphere) and post-treatment condition. Glassy carbon electrode (GCE) modified by the as-obtained carbon-encapsulated mono- and bi-transition metal nanoparticles exhibit excellent electro-catalytic activity for hydrogen production in alkaline water electrolysis. Especially, Ni0.4Co0.6@N-Cs800-b catalyst prepared at 800 °C under an argon flow exhibited the best electrocatalytic performance towards HER. The high HER activity of the Ni0.4Co0.6@N-Cs800-b modified electrode is related to the appropriate nickel-cobalt metal ratio with high crystallinity, complete and homogeneous carbon layers outside of the nickel-cobalt with high conductivity and the synergistic effect of nickel-cobalt alloys that also accelerate electron transfer process.

  15. Corrosion study of iron-cobalt alloys for MRI-based propulsion embedded in untethered microdevices operating in the vascular network.

    Science.gov (United States)

    Pouponneau, Pierre; Savadogo, Oumarou; Napporn, Teko; Yahia, L'hocine; Martel, Sylvain

    2010-04-01

    Our group have shown in an experiment performed in the carotid artery of a living swine that magnetic gradients generated by a clinical magnetic resonance imaging (MRI) system could propel and navigate untethered medical microdevices and micro-nanorobots in the human vasculature. The main problem with these devices is that the metal necessary for magnetic propulsion may corrode and induce cytotoxic effects. The challenge, then, is to find an alloy with low corrosion yet providing an adequate magnetization level for propulsion in often stringent physiological conditions. Because of their high magnetization, we studied the corrosion behavior of two iron-cobalt alloys, Permendur (49% Fe, 49% Co, 2% V) and Vacoflux 17 (81% Fe, 17% Co, 2% Cr), in physiological solution by potentiodynamic polarization assay, surface analysis, and corrosion electrolyte analysis. Both alloys exhibited low corrosion parameters such as a corrosion potential (E(corr)) of -0.57 V/SCE and E(corr) of -0.42 V/SCE for Vacoflux 17. The surface of Permendur samples was homogenously degraded. Vacoflux 17 surface was impaired by cracks and crevices. Both alloys had a stoichiometric dissolution in the electrolyte, and they released enough cobalt to induce cytotoxic effects. This study concluded that Fe-Co alloys could be used preferably in medical microdevices if they were coated so as not to come in contact with physiological solutions.

  16. Resistance Element Welding of Magnesium Alloy/austenitic Stainless Steel

    Science.gov (United States)

    Manladan, S. M.; Yusof, F.; Ramesh, S.; Zhang, Y.; Luo, Z.; Ling, Z.

    2017-09-01

    Multi-material design is increasingly applied in the automotive and aerospace industries to reduce weight, improve crash-worthiness, and reduce environmental pollution. In the present study, a novel variant of resistance spot welding technique, known as resistance element welding was used to join AZ31 Mg alloy to 316 L austenitic stainless steel. The microstructure and mechanical properties of the joints were evaluated. It was found that the nugget consisted of two zones, including a peripheral fusion zone on the stainless steel side and the main fusion zone. The tensile shear properties of the joints are superior to those obtained by traditional resistance spot welding.

  17. Annealed coated air-stable cobalt--rare earth alloy particles

    International Nuclear Information System (INIS)

    Smeggil, J.C.; Charles, R.J.

    1975-01-01

    A process is described for producing novel air-stable coated particles of a magnetic transition metal-rare earth alloy. An organometallic compound which decomposes at a temperature below 500 0 C is heated to produce a metal vapor which is contacted with particles of a transition metal-rare earth alloy to deposit a metal coating thereon. The coated particles are heated at a temperature ranging from 50 to 200 0 C for a period of time sufficient to increase their intrinsic coercive force by at least 10 percent. (U.S.)

  18. Effect of stacking fault energy on high-temperature creep parameters of nickel-cobalt alloys

    International Nuclear Information System (INIS)

    Nerodenko, L.M.; Dabizha, E.V.

    1982-01-01

    Results of creep investigation are discussed for two alloys of the Ni-Co system. In terms of the structural creep model an analysis is made for the effect of stacking fault energy on averaged parameters of the dislocation structure: inovable dislocation density subgrain size, activation volume. The rate of steady-state creep is determined by the process of dislocation passing through the subgrain boundaries with activation energy of 171.0 and 211.5 kJ/mol for the Ni-25% Co and Ni-65% Co alloys, respectively

  19. Mechanical properties of modified low cobalt powder metallurgy Udimet 700 type alloys

    Science.gov (United States)

    Harf, Fredric H.

    1989-01-01

    Eight superalloys derived from Udimet 700 were prepared by powder metallurgy, hot isostatically pressed, heat treated and their tensile and creep rupture properties determined. Several of these alloys displayed properties superior to those of Udimet 700 similarly prepared, in one case exceeding the creep rupture life tenfold. Filter clogging by extracted gamma prime, its measurement and significance are discussed in an appendix.

  20. Recovery of cobalt-rare earth alloy particles by hydration-disintegration in a magnetic field

    International Nuclear Information System (INIS)

    McFarland, C.M.; Lerman, T.B.; Rockwood, A.C.

    1975-01-01

    A process for recovering magnetic alloy particles from a reaction product cake. The cake is placed in a reactor where it is contacted with a flowing water vapor-carrying gas which reacts with its calcium content to disintegrate the cake and produce a hydrated powder comprised substantially of calcium hydroxide and the alloy particles. A magnetic zone is generated into a cross-section of the reactor substantially encircling the inside wall thereof. The zone is generated by at least two poles of opposite polarity running the length of the zone. The hydrated powder is fluidized to dissociate and pass the calcium hydroxide out of the reactor. Finer-sized alloy particles carried by the fluidizing gas into the magnetic zone are subjected to the magnetic field where the poles are rotated or reversed at a rate which reverses the positions of the particles sufficiently to release adherent calcium hydroxide leaving the finer-sized alloy particles substantially within the magnetic zone. (auth)

  1. KTA 625 alloy tube with excellent corrosion resistance and heat resistance

    International Nuclear Information System (INIS)

    Fujiwara, Kazuo; Kadonaga, Toshiki; Kikuma, Seiji.

    1982-01-01

    The problems when seamless tubes are produced by using nickel base 625 alloy (61Ni-22Cr-9Mo-Cb) which is known as a corrosion resistant and heat resistant alloyF were examined, and the confirmation experiment was carried out on its corrosion resistance and heat resistance. Various difficulties have been experienced in the tube making owing to the characteristics due to the chemical composition, but they were able to be solved by the repeated experiments. As for the characteristics of the product, the corrosion resistance was excellent particularly in the environment containing high temperature, high concentration chloride, and also the heat resistance was excellent in the wide temperature range from normal temperature to 1000 deg C. From these facts, the wide fields of application are expected for these alloy tubes, including the evaporation and concentration equipment for radioactive wastes in atomic energy field. Expecting the increase of demand hereafter, Kobe Steel Ltd. examined the problems when seamless tubes are produced from the 625 alloy by Ugine Sejournet process. The aptitude for tube production such as the chemical composition, production process and the product characteristics, the corrosion resistance against chloride, hydrogen sulfide, polythionic and other acids,F the high temperature strength and oxidation resistance are reported. (Kako, I.)

  2. Corrosion resistance of titanium ion implanted AZ91 magnesium alloy

    International Nuclear Information System (INIS)

    Liu Chenglong; Xin Yunchang; Tian Xiubo; Zhao, J.; Chu, Paul K.

    2007-01-01

    Degradable metal alloys constitute a new class of materials for load-bearing biomedical implants. Owing to their good mechanical properties and biocompatibility, magnesium alloys are promising in degradable prosthetic implants. The objective of this study is to improve the corrosion behavior of surgical AZ91 magnesium alloy by titanium ion implantation. The surface characteristics of the ion implanted layer in the magnesium alloys are examined. The authors' results disclose that an intermixed layer is produced and the surface oxidized films are mainly composed of titanium oxide with a lesser amount of magnesium oxide. X-ray photoelectron spectroscopy reveals that the oxide has three layers. The outer layer which is 10 nm thick is mainly composed of MgO and TiO 2 with some Mg(OH) 2 . The middle layer that is 50 nm thick comprises predominantly TiO 2 and MgO with minor contributions from MgAl 2 O 4 and TiO. The third layer from the surface is rich in metallic Mg, Ti, Al, and Ti 3 Al. The effects of Ti ion implantation on the corrosion resistance and electrochemical behavior of the magnesium alloys are investigated in simulated body fluids at 37±1 deg. C using electrochemical impedance spectroscopy and open circuit potential techniques. Compared to the unimplanted AZ91 alloy, titanium ion implantation significantly shifts the open circuit potential (OCP) to a more positive potential and improves the corrosion resistance at OCP. This phenomenon can be ascribed to the more compact surface oxide film, enhanced reoxidation on the implanted surface, as well as the increased β-Mg 12 Al 17 phase

  3. Effects of cobalt in nickel-base superalloys

    Science.gov (United States)

    Tien, J. K.; Jarrett, R. N.

    1983-01-01

    The role of cobalt in a representative wrought nickel-base superalloy was determined. The results show cobalt affecting the solubility of elements in the gamma matrix, resulting in enhanced gamma' volume fraction, in the stabilization of MC-type carbides, and in the stabilization of sigma phase. In the particular alloy studied, these microstructural and microchemistry changes are insufficient in extent to impact on tensile strength, yield strength, and in the ductilities. Depending on the heat treatment, creep and stress rupture resistance can be cobalt sensitive. In the coarse grain, fully solutioned and aged condition, all of the alloy's 17% cobalt can be replaced by nickel without deleteriously affecting this resistance. In the fine grain, partially solutioned and aged condition, this resistance is deleteriously affected only when one-half or more of the initial cobalt content is removed. The structure and property results are discussed with respect to existing theories and with respect to other recent and earlier findings on the impact of cobalt, if any, on the performance of nickel-base superalloys.

  4. Corrosion resistance of Zn-Co-Fe alloy coatings on high strength steel

    NARCIS (Netherlands)

    Lodhi, Z.F.; Mol, J.M.C.; Hovestad, A.; Hoen-Velterop, L. 't; Terryn, H.; Wit, J.H.W.de

    2009-01-01

    The corrosion properties of electrodeposited zinc-cobalt-iron (Zn-Co-Fe) alloys (up to 40 wt.% Co and 1 wt.% Fe) on steel were studied by using various electrochemical techniques and compared with zinc (Zn) and cadmium (Cd) coatings in 3.5% NaCl solution. It was found that with an increase in Co

  5. The 23 to 300 C demagnetization resistance of samarium-cobalt permanent magnets

    Science.gov (United States)

    Niedra, Janis M.; Overton, Eric

    1991-01-01

    The influence of temperature on knee point and squareness of the M-H demagnetization characteristic of permanent magnets is important information for the full utilization of the capabilities of samarium-cobalt magnets at high temperature in demagnetization resistent permanent magnet devices. Composite plots of the knee field and the demagnetizing field required to produce a given magnetic induction swing below remanence were obtained for several commercial Sm2Co17 type magnet samples in the temperature range of 23 to 300 C. Using the knee point to define the limits of operation safe against irreversible demagnetization, such plots are shown to provide an effective overview of the useable regions in the space of temperature-induction swing parameters. The observed second quadrant M-H characteristic squareness is shown, by two measures, to increase gradually with temperature, reaching a peak in the interval 200 to 300 C.

  6. Predicting creep strengths and lifetimes of creep resistant engineering alloys

    Science.gov (United States)

    Zhao, Yanrong; Yao, Hongpeng; Song, Xinli; Jia, Juan; Xiang, Zhidong

    2018-01-01

    The physical basis for predicting the long-term creep strengths and lifetimes at application temperatures using creep parameters determined from short-term creep tests is investigated for complex creep resistant engineering alloys. It is shown that the seemingly unpredictable stress and temperature dependence of minimum creep rate of such alloys can be rationalised using an approach based on the new power law creep equation that incorporate the tensile strength. This is demonstrated using the tensile and creep data measured for two completely different types of alloys: steel 11Cr-2W-0.4Mo-1Cu-Nb-V and Ni base superalloy 15Cr-28Co-4Mo-2.5Ti-3Al. For both alloys, the stress exponent n determined does not depend on temperature and activation energy of creep does not depend on stress. Consequently, it becomes possible to use the new power law creep equation in combination with the Monkman-Grant relationship to predict the long term creep rupture strengths and lifetimes and microstructure stability of the two alloys from short term creep test data. The implications of the results for creep mechanism identification and future microstructure analysis are discussed.

  7. Corrosion resistance of Fe-based amorphous alloys

    International Nuclear Information System (INIS)

    Botta, W.J.; Berger, J.E.; Kiminami, C.S.; Roche, V.; Nogueira, R.P.; Bolfarini, C.

    2014-01-01

    Highlights: ► We report corrosion properties of Fe-based amorphous alloys in different media. ► The Cr-containing alloys had corrosion resistance close to that of Pt in all media. ► The wide range of electrochemical stability is relevant in many industrial domains. -- Abstract: Fe-based amorphous alloys can be designed to present an attractive combination of properties with high corrosion resistance and high mechanical strength. Such properties are clearly adequate for their technological use as coatings, for example, in steel pipes. In this work, we studied the corrosion properties of amorphous ribbons of the following Fe-based compositions: Fe 66 B 30 Nb 4 , [(Fe 0.6 Co 0.4 ) 0.75 B 0.2 Si 0.05 ] 96 Nb 4 , [(Fe 0.7 Co 0.3 ) 0.75 B 0.2 Si 0.05 ] 96 Nb 4 , Fe 56 Cr 23 Ni 5.7 B 16 , Fe 53 Cr 22 Ni 5.6 B 19 and Fe 50 Cr 22 Ni 5.4 B 23 . The ribbons were obtained by rapid solidification using the melt-spinning process, and were characterized by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and optical (OM) and scanning electron microscopy (SEM). The corrosion properties were evaluated by corrosion potential survey and potentiodynamic polarization. The Cr containing alloys, that is the FeCrNiB type of alloys, showed the best corrosion resistance properties with the formation of a stable passive film that ensured a very large passivation plateau

  8. Influence of silicon, copper and cobalt on corrosion cracking and pitting corrosion in 03Kh18N30 steel

    International Nuclear Information System (INIS)

    Shapovalov, Eh.T.; Ul'yanin, E.A.; Kazakova, G.V.; Sorokina, N.A.; Gal'tsov, V.I.

    1983-01-01

    The effect of alloying low carbon 18Cr-30Ni steel with silicon (up to 5.1%), copper (up to 5.4%), cobalt (up to 15.3%) on the resistance to corrosion cracking and pitting corrosion, is studied. Tests on uniaxial tension are carried out in 42% MgCl 2 solution and gravimetric studies in 10% FeCl 3 x6H 2 O. It is established that alloying steel of the Kh18N30 type with silicon increases strength and resistance to corrosion cracking. Copper and cobalt decrease a resistance to pitting corrosion but somewhat increase a resistance to corrosion cracking

  9. Enhancement of wear and corrosion resistance of beta titanium alloy by laser gas alloying with nitrogen

    DEFF Research Database (Denmark)

    Chan, Chi-Wai; Lee, Seunghwan; Smith, Graham

    2016-01-01

    , the quaternary Ti-Nb-Zr-Ta (TNZT) alloys have received the highest attention as a promising replacement for Ti6Al4V due to their lower elastic modulus and outstanding long term stability against corrosion in biological environments. However, the inferior wear resistance of TNZT is still a problem that must......The relatively high elastic modulus coupled with the presence of toxic vanadium (V) in Ti6Al4V alloy has long been a concern in orthopaedic applications. To solve the problem, a variety of non-toxic and low modulus beta-titanium (beta-Ti) alloys have been developed. Among the beta-Ti alloy family...... be resolved before commercialising in the orthopaedic market. In this work, a newly developed laser surface treatment technique was employed to improve the surface properties of Ti-35.3Nb-7.3Zr-5.7Ta alloy. The surface structure and composition of the laser-treated TNZT surface were examined by grazing...

  10. Rapid Prototyping for In Vitro Knee Rig Investigations of Prosthetized Knee Biomechanics: Comparison with Cobalt-Chromium Alloy Implant Material

    Directory of Open Access Journals (Sweden)

    Christian Schröder

    2015-01-01

    Full Text Available Retropatellar complications after total knee arthroplasty (TKA such as anterior knee pain and subluxations might be related to altered patellofemoral biomechanics, in particular to trochlear design and femorotibial joint positioning. A method was developed to test femorotibial and patellofemoral joint modifications separately with 3D-rapid prototyped components for in vitro tests, but material differences may further influence results. This pilot study aims at validating the use of prostheses made of photopolymerized rapid prototype material (RPM by measuring the sliding friction with a ring-on-disc setup as well as knee kinematics and retropatellar pressure on a knee rig. Cobalt-chromium alloy (standard prosthesis material, SPM prostheses served as validation standard. Friction coefficients between these materials and polytetrafluoroethylene (PTFE were additionally tested as this latter material is commonly used to protect pressure sensors in experiments. No statistical differences were found between friction coefficients of both materials to PTFE. UHMWPE shows higher friction coefficient at low axial loads for RPM, a difference that disappears at higher load. No measurable statistical differences were found in knee kinematics and retropatellar pressure distribution. This suggests that using polymer prototypes may be a valid alternative to original components for in vitro TKA studies and future investigations on knee biomechanics.

  11. Rapid Prototyping for In Vitro Knee Rig Investigations of Prosthetized Knee Biomechanics: Comparison with Cobalt-Chromium Alloy Implant Material

    Science.gov (United States)

    Schröder, Christian; Steinbrück, Arnd; Müller, Tatjana; Woiczinski, Matthias; Chevalier, Yan; Müller, Peter E.; Jansson, Volkmar

    2015-01-01

    Retropatellar complications after total knee arthroplasty (TKA) such as anterior knee pain and subluxations might be related to altered patellofemoral biomechanics, in particular to trochlear design and femorotibial joint positioning. A method was developed to test femorotibial and patellofemoral joint modifications separately with 3D-rapid prototyped components for in vitro tests, but material differences may further influence results. This pilot study aims at validating the use of prostheses made of photopolymerized rapid prototype material (RPM) by measuring the sliding friction with a ring-on-disc setup as well as knee kinematics and retropatellar pressure on a knee rig. Cobalt-chromium alloy (standard prosthesis material, SPM) prostheses served as validation standard. Friction coefficients between these materials and polytetrafluoroethylene (PTFE) were additionally tested as this latter material is commonly used to protect pressure sensors in experiments. No statistical differences were found between friction coefficients of both materials to PTFE. UHMWPE shows higher friction coefficient at low axial loads for RPM, a difference that disappears at higher load. No measurable statistical differences were found in knee kinematics and retropatellar pressure distribution. This suggests that using polymer prototypes may be a valid alternative to original components for in vitro TKA studies and future investigations on knee biomechanics. PMID:25879019

  12. Development of a high strength, hydrogen-resistant austenitic alloy

    International Nuclear Information System (INIS)

    Chang, K.M.; Klahn, D.H.; Morris, J.W. Jr.

    1980-08-01

    Research toward high-strength, high toughness nonmagnetic steels for use in the retaining rings of large electrical generators led to the development of a Ta-modified iron-based superalloy (Fe-36 Ni-3 Ti-3 Ta-0.5 Al-1.3 Mo-0.3 V-0.01 B) which combines high strength with good toughness after suitable aging. The alloy did, however, show some degradation in fatigue resistance in gaseous hydrogen. This sensitivity was associated with a deformation-induced martensitic transformation near the fracture surface. The addition of a small amount of chromium to the alloy suppressed the martensite transformation and led to a marked improvement in hydrogen resistance

  13. Radiation resistance of amorphous silicon alloy solar cells

    International Nuclear Information System (INIS)

    Hanak, J.J.; Chen, E.; Myatt, A.; Woodyard, J.R.

    1987-01-01

    The radiation resistance of a-Si alloy solar cells when bombarded by high energy particles is reviewed. The results of investigations of high energy proton radiation resistance of a-Si alloy thin film photovoltaic cells are reported. Irradiations were carried out with 200 keV and 1.00 MeV protons with fluences ranging betweeen 1E11 and 1E15 cm-2. Defect generation and passivation mechanisms were studied using the AM1 conversion efficiency and isochronal anneals. It is concluded that the primary defect generation mechanism results from the knock-on of Si and Ge in the intrinsic layer of the cells. The defect passivation proceeds by the complex annealing of Si and Ge defects and not by the simple migration of hydrogen

  14. Hot corrosion resistance of nickel-chromium-aluminum alloys

    Science.gov (United States)

    Santoro, G. J.; Barret, C. A.

    1977-01-01

    The hot corrosion resistance of nickel-chromium-aluminum alloys was examined by cyclically oxidizing sodium sulfate-coated specimens in still air at 900, 1000, and 1100 C. The compositions tested were within the ternary region: Ni, Ni-50 at.% Cr, and Ni-50 at.% Al. At each temperature the corrosion data were statistically fitted to a third order regression equation as a function of chromium and aluminum contents. From these equations corrosion isopleths were prepared. Compositional regions with the best hot corrosion resistance were identified.

  15. Mass-selected iron-cobalt alloy clusters. Correlation of magnetic and structural properties; Massenselektierte Eisen-Kobalt-Legierungscluster. Korrelation magnetischer und struktureller Eigenschaften

    Energy Technology Data Exchange (ETDEWEB)

    Bulut, Furkan

    2008-10-13

    In this work, I present results concerning structural and magnetic properties of massselected iron-cobalt alloy clusters with diameters between 5 and 15 nm. I have studied the structure of FeCo alloy clusters with high resolution transmission electron microscopy (HRTEM) and scanning tunneling microscopy (STM). I have also investigated the crystalline structure of pure iron and pure cobalt clusters with HRTEM to ensure a reliable determination of the lattice parameter for the alloy clusters. The FeCo nanoparticles have a truncated dodecahedral shape with a CsCl-structure. The clusters were produced with a continuously working arc cluster ion source and subsequently mass-selected with an electrostatic quadrupole deflector. The composition of the alloy clusters was checked with energy dispersive x-ray spectroscopy (EDX). The lateral size distribution was investigated by TEM and the height of the deposited FeCo clusters on the (110) surface of tungsten was determined by STM. Comparing the results I have observed that the supported clusters were flattened due to the high surface energy of W(110). The decrease in height of the mass-selected supported clusters amounts to about 1 nm. Furthermore, element specific magnetic studies performed by means of X-ray magnetic circular dichroism (XMCD) have shown that magnetic moments of Fe{sub 50}Co{sub 50} alloy clusters are in good agreement with the theoretically expected values in the bulk. I have also examined the behavior of the alloy clusters at elevated temperatures. The clusters exhibit an anisotropic melting on the W(110) surface. (orig.)

  16. Designing Nanoscale Precipitates in Novel Cobalt-based Superalloys to Improve Creep Resistance and Operating Temperature

    Energy Technology Data Exchange (ETDEWEB)

    Dunand, David C. [Northwestern Univ., Evanston, IL (United States); Seidman, David N. [Northwestern Univ., Evanston, IL (United States); Wolverton, Christopher [Northwestern Univ., Evanston, IL (United States); Saal, James E. [Northwestern Univ., Evanston, IL (United States); Bocchini, Peter J. [Northwestern Univ., Evanston, IL (United States); Sauza, Daniel J. [Northwestern Univ., Evanston, IL (United States)

    2014-10-01

    High-temperature structural alloys for aerospace and energy applications have long been dominated by Ni-base superalloys, whose strength and creep resistance can be attributed to microstructures consisting of a large volume fraction of ordered (L12) γ'-precipitates embedded in a disordered’(f.c.c.) γ-matrix. These alloys exhibit excellent mechanical behavior and thermal stability, but after decades of incremental improvement are nearing the theoretical limit of their operating temperatures. Conventional Co-base superalloys are solid-solution or carbide strengthened; although they see industrial use, these alloys are restricted to lower-stress applications because the absence of an ordered intermetallic phase places an upper limit on their mechanical performance. In 2006, a γ+γ' microstructure with ordered precipitates analogous to (L12) Ni3Al was first identified in the Co-Al-W ternary system, allowing, for the first time, the development of Co-base alloys with the potential to meet or even exceed the elevated-temperature performance of their Ni-base counterparts. The potential design space for these alloys is complex: the most advanced Ni-base superalloys may contain as many as 8-10 minor alloying additions, each with a specified purpose such as raising the γ' solvus temperature or improving creep strength. Our work has focused on assessing the effects of alloying additions on microstructure and mechanical behavior of γ'-strengthened Co-base alloys in an effort to lay the foundations for understanding this emerging alloy system. Investigation of the size, morphology, and composition of γ' and other relevant phases is investigated utilizing scanning electron microscopy (SEM) and 3-D picosecond ultraviolet local electrode atom probe tomography (APT). Microhardness, compressive yield stress at ambient and elevated temperatures, and compressive high-temperature creep measurements are employed to

  17. Magnetic Properties of Composites of Fe/Co Alloy and Cobalt Doped Magnetite

    Energy Technology Data Exchange (ETDEWEB)

    Dormann, J.L. [LMOV, CNRS-Universite de Versailles (France); Greneche, J.L. [EPEC, URA 807, Universite du Maine (France); Pourroy, G.; Laekamp, S. [GMI-IPCMS (France)

    1998-12-15

    Composites consisting of mixture of a Fe-Co alloy and a mixed Fe-Co ferrite have been studied together with the pure spinel phase extracted from the composite. They are prepared by a new chemical route. Detailed Moessbauer studies allow the determination of the chemical formulas including the Fe and Co populations in the two spinel sites. Moessbauer study under applied field reveals the presence of a randomly canted spin structure in the spinel. The results are in agreement with the magnetization measurements.

  18. Dependence of magnetostriction of iron-cobalt alloys on deformation texture recrystallization and atomic heat treatment

    International Nuclear Information System (INIS)

    Domyshev, V.A.; Ashchepkov, V.T.; Osipov, A.Yu.; Kuznetsova, I.N.; Kuznetsov, N.A.

    1984-01-01

    Results of investigation into the effect of rolling texture and heat treatm ent on change of magnetostriction value of Fe-Co alloys are given. It was established that primary orientations, providing the increase of lambda magnetos triction along the rolling or at an angle to it occur for cold-rolled Fe-Co-2V 50 kf samples depending on heat treatment conditions. It was shown that ordering heat treatment of isotopic Fe-Co samples with maximal order degr ee results as well to lambda increase two times and more. The combined use of t hese effects can widen the possibilities of production of high-magnetostriction materials

  19. Continuous Measurements of Recrystallization and Grain Growth in Cobalt Super Alloys

    Science.gov (United States)

    Keyvani, Mahsa; Garcin, Thomas; Fabrègue, Damien; Militzer, Matthias; Yamanaka, Kenta; Chiba, Akihiko

    2017-05-01

    L605 (20Cr-15W-10Ni wt pct) and CCM (28Cr-6Mo wt pct) cobalt-based superalloys are candidates for a wide range of applications, from gas turbine components to biomedical implants. Attention is currently focused on the optimization of grain structure as an appropriate approach to increase yield stress without affecting significantly the ductility. In this study, the Laser Ultrasonics for Metallurgy (LUMet) technology is used to examine in situ the evolution of the mean grain size associated with recrystallization and grain growth during heat treatments from the cold-rolled state. The recrystallization process is completed at 1373 K (1100 °C) for L605 and 1273 K (1000 °C) for CCM. The subsequent grain growth rate in L605 is larger compared to CCM. Continuous measurements of the grain size evolution are found to be consistent with grain growth affected by solute drag. Through in situ measurements, the laser ultrasonic technology significantly accelerates the determination of metallurgical parameters allowing for fast optimization of process parameters required to meet specific applications.

  20. The α → ω Transformation in Titanium-Cobalt Alloys under High-Pressure Torsion

    Directory of Open Access Journals (Sweden)

    Askar R. Kilmametov

    2017-12-01

    Full Text Available The pressure influence on the α → ω transformation in Ti–Co alloys has been studied during high pressure torsion (HPT. The α → ω allotropic transformation takes place at high pressures in titanium, zirconium and hafnium as well as in their alloys. The transition pressure, the ability of high pressure ω-phase to retain after pressure release, and the pressure interval where α and ω phases coexist depend on the conditions of high-pressure treatment. During HPT in Bridgeman anvils, the high pressure is combined with shear strain. The presence of shear strain as well as Co addition to Ti decreases the onset of the α → ω transition from 10.5 GPa (under quasi-hydrostatic conditions to about 3.5 GPa. The portion of ω-phase after HPT at 7 GPa increases in the following sequence: pure Ti → Ti–2 wt % Co → Ti–4 wt % Co → Ti–4 wt % Fe.

  1. Investigation on wear resistance and corrosion resistance of electron beam cladding co-alloy coating on Inconel617

    Science.gov (United States)

    Liu, Hailang; Zhang, Guopei; Huang, Yiping; Qi, Zhengwei; Wang, Bo; Yu, Zhibiao; Wang, Dezhi

    2018-04-01

    To improve surface properties of Inconel 617 alloy (referred to as 617 alloy), co-alloy coating metallurgically bonded to substrate was prepared on the surface of 617 alloy by electron beam cladding. The microstructure, phase composition, microhardness, tribological properties and corrosion resistance of the coatings were investigated. The XRD results of the coatings reinforced by co-alloy (Co800) revealed the presence of γ-Co, CoCx and Cr23C6 phase as matrix and new metastable phases of Cr2Ni3 and Co3Mo2Si. These hypoeutectic structures contain primary dendrites and interdendritic eutectics. The metallurgical bonding forms well between the cladding layer and the matrix of 617 alloy. In most studied conditions, the co-alloy coating displays a better hardness, tribological performance, i.e., lower coefficient of frictions and wear rates, corrosion resistance in 1 mol L‑1 HCl solution, than the 617 alloy.

  2. Machinability of magnesium and aluminium alloys. Part I: cutting resistance

    International Nuclear Information System (INIS)

    Balout, B.; Songmene, V.; Masounave, J.

    2002-01-01

    Aluminium (2.7 g/cm 3 ) and magnesium (1.7 g/cm 3 ) are two competing light metals with similar mechanical properties and excellent possibilities for recycling. The forming of magnesium is often seen as an impediment to its use. New forming techniques using magnesium shavings are being developed, particularly in Japan. The machining of magnesium alloys by removal of metal raises safety concerns (risk of fire), which limits many potential applications of magnesium. The purpose of this work is to clarify and compare the machining properties of these two types of metal and better understand the mechanisms that may explain the differences in behaviour. Such a comparison could eventually provide an estimate of the cost of producing shavings for the manufacture of aluminium and magnesium parts through forging and extrusion, which would limit environmental pollution. Based on an analysis of cutting resistance during machining, it was demonstrated that magnesium alloys are easier to machine than similar aluminium alloys. Magnesium shavings are shorter than those of 6061-T6, but are especially more regular than those of A356, and their size is independent of cutting speed. It was also demonstrated that the fragility of materials can be characterized based on the results of cutting resistance produced during drilling

  3. The effect of remelting various combinations of new and used cobalt-chromium alloy on the mechanical properties and microstructure of the alloy

    Directory of Open Access Journals (Sweden)

    Sharad Gupta

    2012-01-01

    Conclusion: Repeated remelting of base metal alloy for dental casting without addition of new alloy can affect the mechanical properties of the alloy. Microstructure analysis shows deterioration upon remelting. However, the addition of 25% and 50% (by weight of new alloy to the remelted alloy can bring about improvement both in mechanical properties and in microstructure.

  4. Cobalt release from implants and consumer items and characteristics of cobalt sensitized patients with dermatitis

    DEFF Research Database (Denmark)

    Thyssen, Jacob Pontoppidan; Menne, Torkil; Liden, Carola

    2012-01-01

    -containing dental alloys and revised hip implant components.Results. Six of eight dental alloys and 10 of 98 revised hip implant components released cobalt in the cobalt spot test, whereas none of 50 mobile phones gave positive reactions. The clinical relevance of positive cobalt test reactions was difficult...

  5. Structural relaxation in an amorphous rapidly quenched cobalt-based alloy

    International Nuclear Information System (INIS)

    Fradin, V.; Grynszpan, R.I.; Alves, F.; Houzali, A.; Perron, J.C.

    1995-01-01

    An amorphous melt-spun Co-based alloy (Metglas 2705 MN) is investigated by Doppler Broadening and Positron Lifetime techniques in order to follow the microstructural changes yielded by isochronal annealings before crystallization. The results are correlated with those of Differential Scanning Calorimetry and Coercive Field measurements. The quenched empty spaces underlined by Lifetime measurements are less than one atomic volume in size and migrate without clustering in larger voids. Both Positron Annihilation and Coercive Field investigations suggest that the overall decrease of free volume related to structural relaxation in this amorphous material, proceeds mainly via compositional short-range ordering. These local chemical rearrangements which lead to a partial disorientation of the magnetic moments act as strong pinning points for Bloch Walls. (orig.)

  6. Fitness and retentive force of cobalt-chromium alloy clasps fabricated with repeated laser sintering and milling.

    Science.gov (United States)

    Torii, Mana; Nakata, Toyoki; Takahashi, Kazuya; Kawamura, Noboru; Shimpo, Hidemasa; Ohkubo, Chikahiro

    2018-02-07

    With computer-aided design and computer-aided manufacturing (CAD/CAM), the study was conducted to create a removable partial denture (RPD) framework using repeated laser sintering rather than milling and casting techniques. This study experimentally evaluated the CAM clasp and compared it to a conventional cast clasp. After the tooth die was scanned, an Akers clasp was designed using CAD with and without 50μm of digital relief on the occlusal surface of the tooth die. Cobalt-chromium (Co-Cr) alloy clasps were fabricated using repeated laser sintering (RLS) and milling as one process simultaneously (hybrid manufacturing; HM). The surface roughness of the rest region, gap distances between clasp and tooth die, initial retentive forces, and changes of retentive forces up to 10,000 insertion/removal cycles were measured before and after heat treatment. The HM clasp was compared to the cast clasp and the clasp made by repeated laser sintering only without a milling process. The HM clasp surface was smoother than those of cast and RLS clasps. With the digital relief, the fitness accuracy of the HM clasp improved. The retentive forces of the HM clasps with relief and after heat treatment were significantly greater than for the cast clasp. HM clasps demonstrated a constant or slight decrease of retention up to 10,000 cycles. HM clasp exhibited better fitness accuracy and retentive forces. The possibility of clinically using HM clasps as well as conventional cast clasps can be suggested. Copyright © 2018 Japan Prosthodontic Society. Published by Elsevier Ltd. All rights reserved.

  7. Oxidised zirconium versus cobalt alloy bearing surfaces in total knee arthroplasty: 3D laser scanning of retrieved polyethylene inserts.

    Science.gov (United States)

    Anderson, F L; Koch, C N; Elpers, M E; Wright, T M; Haas, S B; Heyse, T J

    2017-06-01

    We sought to establish whether an oxidised zirconium (OxZr) femoral component causes less loss of polyethylene volume than a cobalt alloy (CoCr) femoral component in total knee arthroplasty. A total of 20 retrieved tibial inserts that had articulated with OxZr components were matched with 20 inserts from CoCr articulations for patient age, body mass index, length of implantation, and revision diagnosis. Changes in dimensions of the articular surfaces were compared with those of pristine inserts using laser scanning. The differences in volume between the retrieved and pristine surfaces of the two groups were calculated and compared. The loss of polyethylene volume was 122 mm 3 (standard deviation (sd) 87) in the OxZr group and 170 mm 3 (sd 96) in the CoCr group (p = 0.033). The volume loss in the OxZr group was also lower in the medial (72 mm 3 (sd 67) versus 92 mm 3 (sd 60); p = 0.096) and lateral (49 mm 3 (sd 36) versus 79 mm 3 (sd 61); p = 0.096) compartments separately, but these differences were not significant. Our results corroborate earlier findings from in vitro testing and visual retrieval analysis which suggest that polyethylene volume loss is lower with OxZr femoral components. Since both OxZr and CoCr are hard surfaces that would be expected to create comparable amounts of polyethylene creep, the differences in volume loss may reflect differences in the in vivo wear of these inserts. Cite this article: Bone Joint J 2017;99-B:793-8. ©2017 The British Editorial Society of Bone & Joint Surgery.

  8. Alloy SCR-3 resistant to stress corrosion cracking

    International Nuclear Information System (INIS)

    Kowaka, Masamichi; Fujikawa, Hisao; Kobayashi, Taiki

    1977-01-01

    Austenitic stainless steel is used widely because the corrosion resistance, workability and weldability are excellent, but the main fault is the occurrence of stress corrosion cracking in the environment containing chlorides. Inconel 600, most resistant to stress corrosion cracking, is not necessarily safe under some severe condition. In the heat-affected zone of SUS 304 tubes for BWRs, the cases of stress corrosion cracking have occurred. The conventional testing method of stress corrosion cracking using boiling magnesium chloride solution has been problematical because it is widely different from actual environment. The effects of alloying elements on stress corrosion cracking are remarkably different according to the environment. These effects were investigated systematically in high temperature, high pressure water, and as the result, Alloy SCR-3 with excellent stress corrosion cracking resistance was found. The physical constants and the mechanical properties of the SCR-3 are shown. The states of stress corrosion cracking in high temperature, high pressure water containing chlorides and pure water, polythionic acid, sodium phosphate solution and caustic soda of the SCR-3, SUS 304, Inconel 600 and Incoloy 800 are compared and reported. (Kako, I.)

  9. Redox-complexometric determination of iron and cobalt and its application to the analysis of multi-component alloys.

    Science.gov (United States)

    Horácek, J; Pribil, R

    1969-01-01

    A redox-complexometric determination of iron and cobalt is based on potentiometric titration of iron with EDTA, followed by that of cobalt with iron(III) chloride after addition of 1,10-phenanthroline. This method simplifies the complexometric analysis of more complicated materials.

  10. New corrosion resistant alloys on the base of titanium and high-chromium steels

    International Nuclear Information System (INIS)

    Tomashov, N.D.; Chernova, G.P.

    1975-01-01

    It is shown that stability of titanium alloys, with α-structure (OT-4, AT3,AT6) and high-strength α+β or pure β-structure (BT-14; BT-15), in hydrochloric acid solutions may be significantly improved due to additional alloying by minor additions of Pd(0,2%) similar to pure titanium. Additions of 0,2% Pd also significantly improve acid resistance of alloys of the Fe-Cr system. The highest corrosion resistance has Fe,40%Cr,0,2%Pd alloy. This alloy is stable in 20-40%H 2 SO 4 and 1% HCl at 100 deg C

  11. Air- and Water-Resistant Noble Metal Coated Ferromagnetic Cobalt Nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Lentijo-Mozo, Sergio; Tan, Reasmey P.; Garcia-Marcelot, Cécile; Altantzis, Thomas; Fazzini, Pier-Francesco; Hungria, Teresa; Cormary, Benoit; Gallagher, James R.; Miller, Jeffrey T.; Martinez, Herve; Schrittwieser, Stefan; Schotter, Joerg; Respaud, Marc; Bals, Sara; Tendeloo, Gustaaf Van; Gatel, Christophe; Soulantica, Katerina

    2015-03-24

    Cobalt nanorods possess ideal magnetic properties for applications requiring magnetically hard nanoparticles. However, their exploitation is undermined by their sensitivity toward oxygen and water, which deteriorates their magnetic properties. The development of a continuous metal shell inert to oxidation could render them stable, opening perspectives not only for already identified applications but also for uses in which contact with air and/or aqueous media is inevitable. However, the direct growth of a conformal noble metal shell on magnetic metals is a challenge. Here, we show that prior treatment of Co nanorods with a tin coordination compound is the crucial step that enables the subsequent growth of a continuous noble metal shell on their surface, rendering,them air- and water-resistant, while conserving the monocrystallity, metallicity and the Magnetic properties of the Co core. Thus, the as-synthesized tore shell ferromagnetic nanorods combine high;Magnetization and strong uniaxial Magnetic anisotropy, even after exposure to air and water, and hold promise for successful implementation in in vitro biodiagnostics requiring probes Of high magnetization and anisotropic shape.

  12. Air- and Water-Resistant Noble Metal Coated Ferromagnetic Cobalt Nanorods

    Energy Technology Data Exchange (ETDEWEB)

    Lentijo-Mozo, Sergio [Laboratoire de Physique et Chimie des Nano-objets (LPCNO), Université de Toulouse, INSA, UPS, CNRS, 135 avenue de Rangueil, 31077 Toulouse, France; Tan, Reasmey P. [Laboratoire de Physique et Chimie des Nano-objets (LPCNO), Université de Toulouse, INSA, UPS, CNRS, 135 avenue de Rangueil, 31077 Toulouse, France; Garcia-Marcelot, Cécile [Laboratoire de Physique et Chimie des Nano-objets (LPCNO), Université de Toulouse, INSA, UPS, CNRS, 135 avenue de Rangueil, 31077 Toulouse, France; Centre d’Elaboration de Matériaux et d’Etudes Structurales (CEMES-CNRS), 29 rue Jeanne Marvig, B.P. 94347, 31055 Toulouse, France; Altantzis, Thomas [Electron Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium; Fazzini, Pier-Francesco [Laboratoire de Physique et Chimie des Nano-objets (LPCNO), Université de Toulouse, INSA, UPS, CNRS, 135 avenue de Rangueil, 31077 Toulouse, France; Hungria, Teresa [Laboratoire de Physique et Chimie des Nano-objets (LPCNO), Université de Toulouse, INSA, UPS, CNRS, 135 avenue de Rangueil, 31077 Toulouse, France; Cormary, Benoit [Laboratoire de Physique et Chimie des Nano-objets (LPCNO), Université de Toulouse, INSA, UPS, CNRS, 135 avenue de Rangueil, 31077 Toulouse, France; Gallagher, James R. [Chemical Science and Engineering Division, Argonne National Laboratory, 9700 S Cass Avenue, Argonne, Illinois 60439, United States; Miller, Jeffrey T. [Chemical Science and Engineering Division, Argonne National Laboratory, 9700 S Cass Avenue, Argonne, Illinois 60439, United States; Martinez, Herve [IPREM-ECP CNRS UMR 5254, Université de Pau, Hélioparc Pau Pyrénées, 2 av. Pierre Angot, 64053 Pau Cedex 9, France; Schrittwieser, Stefan [Molecular Diagnostics, AIT Austrian Institute of Technology, Vienna, Donau City Strasse 1, 1220 Vienna, Austria; Schotter, Joerg [Molecular Diagnostics, AIT Austrian Institute of Technology, Vienna, Donau City Strasse 1, 1220 Vienna, Austria; Respaud, Marc [Laboratoire de Physique et Chimie des Nano-objets (LPCNO), Université de Toulouse, INSA, UPS, CNRS, 135 avenue de Rangueil, 31077 Toulouse, France; Bals, Sara [Electron Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium; Tendeloo, Gustaaf Van [Electron Microscopy for Materials Research (EMAT), University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp, Belgium; Gatel, Christophe [Centre d’Elaboration de Matériaux et d’Etudes Structurales (CEMES-CNRS), 29 rue Jeanne Marvig, B.P. 94347, 31055 Toulouse, France; Soulantica, Katerina [Laboratoire de Physique et Chimie des Nano-objets (LPCNO), Université de Toulouse, INSA, UPS, CNRS, 135 avenue de Rangueil, 31077 Toulouse, France

    2015-02-25

    Cobalt nanorods possess ideal magnetic properties for applications requiring magnetically hard nanoparticles. However, their exploitation is undermined by their sensitivity toward oxygen and water, which deteriorates their magnetic properties. The development of a continuous metal shell inert to oxidation could render them stable, opening perspectives not only for already identified applications but also for uses in which contact with air and/or aqueous media is inevitable. However, the direct growth of a conformal noble metal shell on magnetic metals is a challenge. Here, we show that prior treatment of Co nanorods with a tin coordination compound is the crucial step that enables the subsequent growth of a continuous noble metal shell on their surface, rendering them air- and water-resistant, while conserving the monocrystallity, metallicity and the magnetic properties of the Co core. Thus, the as-synthesized core–shell ferromagnetic nanorods combine high magnetization and strong uniaxial magnetic anisotropy, even after exposure to air and water, and hold promise for successful implementation in in vitro biodiagnostics requiring probes of high magnetization and anisotropic shape.

  13. Construction of an apparatus for nuclear orientation measurements at low temperatures. Application to neodymium-cobalt alloy; Realisation d'un appareil pour des mesures d'orientation nucleaire a basse temperature. Application a l'alliage neodyme-cobalt

    Energy Technology Data Exchange (ETDEWEB)

    Mayer, E. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1965-10-01

    We describe experiments along which has been studied the anisotropy of {gamma} radiations emitted by oriented nuclei. We have used the great hyperfine fields acting on nuclei in ferromagnetic metals so as to produce alignment at low temperature. By irradiation we obtained a few cobalt 60 nuclei in our samples which were then cooled down to 0,01 K. The anisotropic rate of the 1,33 MeV {gamma} radiation was measured in function of the sample temperature, using as thermometer the anisotropy of {gamma} radiation emitted by cobalt 60 nuclei in a cobalt single crystal. Cobalt 60 was lined up in a cobalt nickel alloy (40% Ni). The hyperfine field at the cobalt was measured compared to the effective field in metallic cobalt: Heff(Co Ni)/Heff(Co metal) = 0.71 {+-} 0.12. These results are in good agreement with specific heat measurements made previously. Cobalt 60 has been polarised in a neodymium-cobalt alloy (NdCo{sub 5}). The field at the cobalt in NdCo{sub 5} has been measured compared to the field in metallic cobalt and taking the non-saturation into account we found 165000 oersteds < Heff(NdCo{sub 5}) < 220000 oersteds. (author) [French] Nous decrivons des experiences au cours desquelles nous avons etudie l'anisotropie de rayonnements {gamma} emis par des noyaux orientes. Nous avons utilise les grands champs hyperfins agissant sur las noyaux dans les metaux ferromagnetiques pour produire l'alignement a basse temperature. Par irradiation nous avons obtenu quelques noyaux de cobalt 60 dans nos echantillons qui furent ensuite refroidis a 0,01 K. Le degre d'anisotropie du rayonnement {gamma} de 1,33 MeV fut mesure en fonction de la temperature de l'echantillon en utilisant l'anisotropie du rayonnement {gamma} de noyaux de cobalt 60 dans un monocristal de cobalt metallique utilise comme thermometre. Le cobalt 60 a ete aligne dans un alliage de cobalt-nickel (40% Ni). Le champ hyperfin au niveau du cobalt a ete mesure par rapport au champ effectif

  14. Iron-based alloys with corrosion resistance to oxygen-sulfur mixed gases

    Science.gov (United States)

    Natesan, Krishnamurti

    1992-01-01

    An iron-based alloy with improved performance with exposure to oxygen-sulfur mixed gases with the alloy containing about 9-30 wt. % Cr and a small amount of Nb and/or Zr implanted on the surface of the alloy to diffuse a depth into the surface portion, with the alloy exhibiting corrosion resistance to the corrosive gases without bulk addition of Nb and/or Zr and without heat treatment at temperatures of 1000.degree.-1100.degree. C.

  15. Heat treatment of NiCrFe alloy to optimize resistance to intergrannular stress corrosion

    Science.gov (United States)

    Steeves, Arthur F.; Bibb, Albert E.

    1984-01-01

    A process of producing a NiCrFe alloy having a high resistance to stress corrosion cracking comprising heating a NiCrFe alloy to a temperature sufficient to enable the carbon present in the alloy body in the form of carbide deposits to enter into solution, rapidly cool the alloy body, and heat the cooled body to a temperature between 1100.degree. to 1500.degree. F. for about 1 to 30 hours.

  16. Heat treatment of NiCrFe alloy 600 to optimize resistance to intergranular stress corrosion

    Science.gov (United States)

    Steeves, A.F.; Bibb, A.E.

    A process of producing a NiCrFe alloy having a high resistance to stress corrosion cracking comprises heating a NiCrFe alloy to a temperature sufficient to enable the carbon present in the alloy body in the form of carbide deposits to enter into solution, rapidly cooling the alloy body, and heating the cooled body to a temperature between 1100 to 1500/sup 0/F for about 1 to 30 hours.

  17. Comparative Evaluation of Metal-ceramic Bond Strengths of Nickel Chromium and Cobalt Chromium Alloys on Repeated Castings: An In vitro Study.

    Science.gov (United States)

    Atluri, Kaleswara Rao; Vallabhaneni, Tapan Teja; Tadi, Durga Prasad; Vadapalli, Sriharsha Babu; Tripuraneni, Sunil Chandra; Averneni, Premalatha

    2014-09-01

    Recasting the base metal alloys is done as a routine procedure in the dental laboratories whenever there is casting failure or to decrease the unit cost of a fixed partial denture. However, this procedure may affect the metal ceramic bond. Furthermore, it is unclear, as to which test closely predicts the bond strength of metal-ceramic interface. The aim was to compare the bond strength of nickel chromium (Ni-Cr) and cobalt chromium (Co-Cr) alloys with dental ceramic on repeated castings using shear bond test with a custom made apparatus. Sixty metal ceramic samples were prepared using Wiron 99 and Wirobond C, respectively. Three subgroups were prepared for each of the groups. The first subgroup was prepared by casting 100% fresh alloy. The second and third subgroups were prepared by adding 50% of fresh alloy and the remnants of the previous cast alloy. The bond load (N) between alloy and dental porcelain was evaluated using universal testing machine using a crosshead speed of 1 mm/min, which had a 2500-kgf load cell. Mean values were compared using oneway analysis of variance with post-hoc Tukey's test and Student's t-test. The mean shear bond load of A0 (842.10N) was significantly higher than the load of A1 (645.50N) and A2 (506.28N). The mean shear bond load of B0 (645.57N) was significantly higher than the load of B1 (457.35N) and B2 (389.30N). Significant reduction in the bond strength was observed with the addition of the first recast alloy (A1 and B1) compared with the addition of second recast alloy (A2 and B2). Ni-Cr alloys (664.63N) showed higher bond strengths compared to that of Co-Cr alloys (497.41N). The addition of previously used base metal dental alloy for fabricating metal ceramic restorations is not recommended.

  18. M-H characteristics and demagnetization resistance of samarium-cobalt permanent magnets to 300 C

    Science.gov (United States)

    Niedra, Janis M.

    1992-01-01

    The influence of temperature on the M-H demagnetization characteristics of permanent magnets is important information for the full utilization of the capabilities of samarium-cobalt magnets at high temperatures in demagnetization-resistant permanent magnet devices. In high temperature space power converters, such as free-piston Stirling engine driven linear alternators, magnet demagnetization can occur as a long-term consequence of thermal agitation of domains and of metallurgical change, and also as an immediate consequence of too large an applied field. Investigated here is the short-term demagnetization resistance to applied fields derived from basic M-H data. This quasistatic demagnetization data was obtained for commercial, high-intrinsic-coercivity, Sm2Co17-type magnets from 5 sources, in the temperature range 23 to 300 C. An electromagnet driven, electronic hysteresigraph was used to test the 1-cm cubic samples. The observed variation of the 2nd quadrant M-H characteristics was a typical rapid loss of M-coercivity and a relatively lesser loss of remanence with increasing temperature. The 2nd quadrant M-H curve knee point is used to define the limits of operation safe against irreversible demagnetization due to an excessive bucking field for a given flux density swing at temperature. Such safe operating area plots are shown to differentiate the high temperature capabilities of the samples from different sources. For most of the samples, their 2nd quadrant M-H loop squareness increased with temperature, reaching a peak or a plateau above 250 C.

  19. Investigation of corrosion resistance of alloys with high mechanical characteristics in some environments of food industry

    International Nuclear Information System (INIS)

    Tremoureux, Yves

    1978-01-01

    This research thesis aimed at improving knowledge in the field of stress-free corrosion of alloys with high mechanical characteristics in aqueous environments, at highlighting some necessary aspects of their behaviour during cleaning or disinfection, and at selecting alloys which possess a good stress-free corrosion resistance in view of a later investigation of their stress corrosion resistance. After a presentation of the metallurgical characteristics of high mechanical strength alloys and the report of a bibliographical study on corrosion resistance of these alloys, the author presents and discusses the results obtained in the study of a possible migration of metallic ions in a milk product which is submitted to a centrifugation, and of the corrosion resistance of selected alloys with respect to the different media they will be in contact with during ultra-centrifugation. The following alloys have been used in this research: Marval 18, Marphynox, Marval X12, 17-4PH steel, Inconel 718 [fr

  20. Iron-niobium-aluminum alloy having high-temperature corrosion resistance

    Science.gov (United States)

    Hsu, Huey S.

    1988-04-14

    An alloy for use in high temperature sulfur and oxygen containing environments, having aluminum for oxygen resistance, niobium for sulfur resistance and the balance iron, is discussed. 4 figs., 2 tabs.

  1. On the resistivity of metal-tellurium alloys for low concentrations of tellurium

    International Nuclear Information System (INIS)

    Gorecki, J.

    1982-04-01

    The resistivity and thermoelectric power of metal-tellurium liquid alloys have been discussed for the case of small tellurium concentration. Nearly free electron model of conduction band has been used. The rapid increase of resistivity in transition metal-tellurium alloys has been predicted. (author)

  2. The effect of metal primer application and Nd:YAG laser irradiation on the shear-bond strength between polymethyl methacrylate and cobalt-chromium alloy.

    Science.gov (United States)

    Yilmaz, Asude; Akyil, Musa Şamil; Hologlu, Bilal

    2011-01-01

    The purpose of this study was to compare the shear-bond strengths (SBSs) of an acrylic resin and a cobalt-chromium (Co-Cr) alloy after applying a metal primer, Nd:YAG laser irradiation, or both to the sandblasted surface of the Co-Cr alloy. The serviceability of a removable partial denture (RPD) is dependent on the bond strength at the resin-alloy interface. No previously published studies exist on the use of Nd:YAG lasers for preparing the surface of a Co-Cr alloy in an RPD to obtain a high-strength bond between PMMA and the alloy. One-hundred twenty Co-Cr alloy specimens were sandblasted and randomly assigned to four equal groups: Group I, sandblasting; Group II, sandblasting + metal primer; Group III, sandblasting + Nd:YAG laser; and Group IV, sandblasting + Nd:YAG laser + metal primer. To establish the most appropriate fluence for modifying the surface of the sandblasted cast specimens, we conducted a preliminary study. Nd:YAG laser irradiation at a fluence of 46.9 J/cm(2) was selected. After the various surface treatments, each alloy specimen was embedded in PMMA to determine the SBS between PMMA and the alloy. Group II and III specimens exhibited higher SBSs than did those of the Group I specimens (p < 0.05), and Group IV specimens showed higher SBSs than did those of the Group II and III specimens (p < 0.05). A significant difference existed in failure types among groups (p < 0.05). Failure type was predominantly adhesive for groups I and III, but predominantly mixed for groups II and IV. Nd:YAG laser irradiation at a fluence of 46.9 J/cm(2) roughens the sandblasted surface of a Co-Cr alloy and increases the strength of the bond between PMMA and the alloy. This bond strength can be increased further by applying a metal primer to the laser-irradiated surface.

  3. Effects of Cobalt on Structure, Microchemistry and Properties of a Wrought Nickel-Base Superalloy

    Science.gov (United States)

    Jarrett, Robert N.; Tien, John K.

    1982-06-01

    Cobalt in a 17 pct cobalt containing wrought nickel-base superalloy is systematically substituted for by nickel in order to determine the role of cobalt. The eventual goal is to reduce the levels of cobalt, a critical strategic element, in superalloys. It is found that the strengthening γ microstructure is highly heat treatment sensitive. Reducing cobalt did not result in a reduction of the fine γ precipitates after a coarse grain type (blading) heat treatment, but did after a fine grain type (disk) heat treatment. Representative mechanical properties were determined for each case to isolate microstructural and microchemistry effects. Ambient yield strength and tensile strength were seen to decrease by no more than 15 pct and 7 pct, respectively, even when all the cobalt was removed. The decrease in strength is quantitatively discussed and shown to be consistent with the observed microstructural results and microchemistry results obtained using STEM/EDS. Elevated temperature creep and stress rupture resistances were concluded to be affected by alloy cobalt content through its effect on strengthening γ volume fraction. Significant decreases in these properties were observed for the lower cobalt content alloys. Long term aging, precipitate coarsening, and carbide stability results are also presented and discussed.

  4. Enthalpy Effect of Adding Cobalt to Liquid Sn-3.8Ag-0.7Cu Lead-Free Solder Alloy: Difference between Bulk and Nanosized Cobalt.

    Science.gov (United States)

    Yakymovych, Andriy; Kaptay, George; Roshanghias, Ali; Flandorfer, Hans; Ipser, Herbert

    2016-01-28

    Heat effects for the addition of Co in bulk and nanosized forms into the liquid Sn-3.8Ag-0.7Cu alloy were studied using drop calorimetry at four temperatures between 673 and 1173 K. Significant differences in the heat effects between nano and bulk Co additions were observed. The considerably more exothermic values of the measured enthalpy for nano Co additions are connected with the loss of the surface enthalpy of the nanoparticles due to the elimination of the surface of the nanoparticles upon their dissolution in the liquid alloy. This effect is shown to be independent of the calorimeter temperature (it depends only on the dropping temperature through the temperature dependence of the surface energy of the nanoparticles). Integral and partial enthalpies of mixing for Co in the liquid SAC-alloy were evaluated from the experimental data.

  5. Influence of carbides and microstructure of CoCrMo alloys on their metallic dissolution resistance.

    Science.gov (United States)

    Valero-Vidal, C; Casabán-Julián, L; Herraiz-Cardona, I; Igual-Muñoz, A

    2013-12-01

    CoCrMo alloys are passive and biocompatible materials widely used as joint replacements due to their good mechanical properties and corrosion resistance. Electrochemical behaviour of thermal treated CoCrMo alloys with different carbon content in their bulk alloy composition has been analysed. Both the amount of carbides in the CoCrMo alloys and the chemical composition of the simulated body fluid affect the electrochemical properties of these biomedical alloys, thus passive dissolution rate was influenced by the mentioned parameters. Lower percentage of carbon in the chemical composition of the bulk alloy and thermal treatments favour the homogenization of the surface (less amount of carbides), thus increasing the availability of Cr to form the oxide film and improving the corrosion resistance of the alloy. © 2013.

  6. Jewellery: alloy composition and release of nickel, cobalt and lead assessed with the EU synthetic sweat method.

    Science.gov (United States)

    Hamann, Dathan; Thyssen, Jacob P; Hamann, Carsten R; Hamann, Curtis; Menné, Torkil; Johansen, Jeanne D; Spiewak, Radoslaw; Maibach, Howard; Lundgren, Lennart; Lidén, Carola

    2015-10-01

    Several studies have shown nickel and cobalt release from jewellery by using spot tests, but the metal composition of jewellery is largely unknown. To evaluate the metal composition of a large worldwide sample of mainly inexpensive jewellery items, and investigate the release of nickel, cobalt and lead from a subsample by using EN 1811:1998-required methods. A total of 956 metallic jewellery components were examined with X-ray fluorescence spectroscopy. A subsample of 96 jewellery items purchased in the United States were investigated for nickel, cobalt and lead release by the use of artificial sweat immersion and plasma optical emission spectroscopy. Eighteen elements were detected. The 10 most frequently occurring were, in order of frequency, copper, iron, zinc, nickel, silver, chromium, tin, manganese, lead, and cobalt. Release of nickel was noted from 79 of the 96 US samples (0.01-98 µg/cm(2) /week), release of cobalt from 35 samples (0.02-0.5 µg/cm(2) /week), and release of lead from 37 samples (0.03-2718 µg/cm(2) /week). We present here a comprehensive list of the most frequently encountered metals in jewellery and fashion accessories. Different allergenic and non-allergenic metals are utilized. We also report the frequent release of nickel, cobalt and lead from these objects, despite legislative restrictions. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  7. Influence of inorganic acid pickling on the corrosion resistance of magnesium alloy AZ31 sheet

    DEFF Research Database (Denmark)

    Nwaogu, Ugochukwu Chibuzoh; Blawert, C.; Scharnagl, N.

    2009-01-01

    Surface contaminants as a result of thermo-mechanical processing of magnesium alloys, e.g. sheet rolling, can have a negative effect on the corrosion resistance of magnesium alloys. Especially contaminants such as Fe, Ni and Cu, left on the surface of magnesium alloys result in the formation...... of micro-galvanic couples and can therefore increase corrosion attack on these alloys. Due to this influence they should be removed to obtain good corrosion resistance. In this study, the effect of inorganic acid pickling on the corrosion behaviour of a commercial AZ31 magnesium alloy sheet...... the corrosion resistance of the alloy. The cleaning efficiency of the three acids used and the corrosion protection mechanisms were found to be remarkably different. Best corrosion results were obtained with nitric acid, followed closely by phosphoric acid. Only the sulphuric acid failed more or less when...

  8. Investigation on some factors affecting crack formation in high resistance aluminum alloys

    Directory of Open Access Journals (Sweden)

    A. Brotzu

    2017-10-01

    Full Text Available Aluminum alloys having good mechanical properties are Al-ZnMg alloys (7xxx and Al-Cu-Li alloys (Weldalite. These alloys may be subjected to stress corrosion cracking. In order to overcome this problem the Al 7050 alloy has been developed and it is widely used for aerospace applications. Despite that, some components made of this alloy cracked during the manufacturing process including machining and chemical anodization. In a previous work cracked Al 7050 components have been analyzed in order to identify possible causes of crack formation. In this work the susceptibility of this alloy to intergranular corrosion has been analysed and compared with that of other high resistance aluminum alloys

  9. Characterization of Cobalt F-75 powder for biomedical application

    International Nuclear Information System (INIS)

    Zuraidawani, C.D.; Shamsul, J.B.; Fazlul, B.; Nur Hidayah, A.Z.

    2007-01-01

    Cobalt F-75 alloys is commonly used for surgical implants because of their strength, corrosion resistance, non-magnetic behaviour and biocompatibility. In this paper, gas atomized of Cobalt F-75 powders were selected for evaluation. These powders supplied by Sandvik Osprey Ltd. The characteristics of these powders were investigated by using particle size analysis, X-ray Diffraction (XRD), X-ray Fluorescence (XRF) and Scanning Electron Microscope (SEM). Two different powder sizes (8.8 μm and 11.5 μm) have showed spherical morphology and the value of densities are 7.9 and 7.6 g/cm 3 respectively. (author)

  10. Study on corrosion resistance of high - entropy alloy in medium acid liquid and chemical properties

    International Nuclear Information System (INIS)

    Florea, I; Buluc, G; Florea, R M; Carcea, I; Soare, V

    2015-01-01

    High-entropy alloy is a new alloy which is different from traditional alloys. The high entropy alloys were started in Tsing Hua University of Taiwan since 1995 by Yeh et al. Consisting of a variety of elements, each element occupying a similar compared with other alloy elements to form a high entropy. We could define high entropy alloys as having approximately equal concentrations, made up of a group of 5 to 11 major elements. In general, the content of each element is not more than 35% by weight of the alloy. During the investigation it turned out that this alloy has a high hardness and is also corrosion proof and also strength and good thermal stability. In the experimental area, scientists used different tools, including traditional casting, mechanical alloying, sputtering, splat-quenching to obtain the high entropy alloys with different alloying elements and then to investigate the corresponding microstructures and mechanical, chemical, thermal, and electronic performances. The present study is aimed to investigate the corrosion resistance in a different medium acid and try to put in evidence the mechanical properties. Forasmuch of the wide composition range and the enormous number of alloy systems in high entropy alloys, the mechanical properties of high entropy alloys can vary significantly. In terms of hardness, the most critical factors are: hardness/strength of each composing phase in the alloy, distribution of the composing phases. The corrosion resistance of an high entropy alloy was made in acid liquid such as 10%HNO 3 -3%HF, 10%H 2 SO 4 , 5%HCl and then was investigated, respectively with weight loss experiment. Weight loss test was carried out by put the samples into the acid solution for corrosion. The solution was maintained at a constant room temperature. The liquid formulations used for tests were 3% hydrofluoric acid with 10% nitric acid, 10% sulphuric acid, 5% hydrochloric acid. Weight loss of the samples was measured by electronic scale. (paper)

  11. Regulation of the Cobalt/Nickel Efflux Operon dmeRF in Agrobacterium tumefaciens and a Link between the Iron-Sensing Regulator RirA and Cobalt/Nickel Resistance.

    Science.gov (United States)

    Dokpikul, Thanittra; Chaoprasid, Paweena; Saninjuk, Kritsakorn; Sirirakphaisarn, Sirin; Johnrod, Jaruwan; Nookabkaew, Sumontha; Sukchawalit, Rojana; Mongkolsuk, Skorn

    2016-08-01

    The Agrobacterium tumefaciens C58 genome harbors an operon containing the dmeR (Atu0890) and dmeF (Atu0891) genes, which encode a transcriptional regulatory protein belonging to the RcnR/CsoR family and a metal efflux protein belonging to the cation diffusion facilitator (CDF) family, respectively. The dmeRF operon is specifically induced by cobalt and nickel, with cobalt being the more potent inducer. Promoter-lacZ transcriptional fusion, an electrophoretic mobility shift assay, and DNase I footprinting assays revealed that DmeR represses dmeRF transcription through direct binding to the promoter region upstream of dmeR A strain lacking dmeF showed increased accumulation of intracellular cobalt and nickel and exhibited hypersensitivity to these metals; however, this strain displayed full virulence, comparable to that of the wild-type strain, when infecting a Nicotiana benthamiana plant model under the tested conditions. Cobalt, but not nickel, increased the expression of many iron-responsive genes and reduced the induction of the SoxR-regulated gene sodBII Furthermore, control of iron homeostasis via RirA is important for the ability of A. tumefaciens to cope with cobalt and nickel toxicity. The molecular mechanism of the regulation of dmeRF transcription by DmeR was demonstrated. This work provides evidence of a direct interaction of apo-DmeR with the corresponding DNA operator site in vitro The recognition site for apo-DmeR consists of 10-bp AT-rich inverted repeats separated by six C bases (5'-ATATAGTATACCCCCCTATAGTATAT-3'). Cobalt and nickel cause DmeR to dissociate from the dmeRF promoter, which leads to expression of the metal efflux gene dmeF This work also revealed a connection between iron homeostasis and cobalt/nickel resistance in A. tumefaciens. Copyright © 2016, American Society for Microbiology. All Rights Reserved.

  12. Electrochemical machining of burn-resistant Ti40 alloy

    Directory of Open Access Journals (Sweden)

    Xu Zhengyang

    2015-08-01

    Full Text Available This study investigates the feasibility of using electrochemical machining (ECM to produce critical aeroengine components from a new burn-resistant titanium alloy (Ti40, thereby reducing costs and improving efficiency relative to conventional mechanical machining. Through this, it is found that an aqueous mix of sodium chloride and potassium bromide provides the optimal electrolyte and that the surface quality of the Ti40 workpiece is improved by using a pulsed current of 1 kHz rather than a direct current. Furthermore, the quality of cavities produced by ECM and the overall material removal rate are determined to be dependent on a combination of operating voltage, electrolyte inlet pressure, cathode feeding rate and electrolyte concentration. By optimizing these parameters, a surface roughness of 0.371 μm has been achieved in conjunction with a specific removal rate of more than 3.1 mm3/A·min.

  13. Chromate-free corrosion resistant conversion coatings for aluminum alloys

    Energy Technology Data Exchange (ETDEWEB)

    Buchheit, R.G.; Drewien, C.A.; Martinez, M.A. [Sandia National Labs., Albuquerque, NM (United States); Stoner, G.E. [Univ. of Virginia, Charlottesville, VA (United States). Dept. of Materials Science

    1995-03-01

    Inorganic polycrystalline hydrotalcite, Li{sub 2}[Al{sub 2}(OH){sub 6}]{sub 2}{center_dot}CO{sub 3}{center_dot}3H{sub 2}O, coatings can be formed on aluminum and aluminum alloys by exposure to alkaline lithium carbonate solutions. This process is conducted using methods similar to traditional chromate conversion coating procedures, but does not use or produce toxic chemicals. The coating provides anodic protection and delays the onset of pitting during anodic polarization. Cathodic reactions are also inhibited which may also contribute to corrosion protection. Recent studies have shown that corrosion resistance can be increased by sealing hydrotalcite coated surfaces to transition metal salt solutions including Ce(NO{sub 3}){sub 3}, KMnO{sub 4} and Na{sub 2}MoO{sub 4}. Results from these studies are also reported.

  14. The fracture resistance of 1420 and 1421 Al-Mg-Li alloys

    Energy Technology Data Exchange (ETDEWEB)

    Birt, M.J.; Hafley, R.A.; Wagner, J.A.; Lisagor, W.B. (NASA Langley Research Center, Hampton, VA (United States))

    1993-04-15

    Aluminum-magnesium-lithium alloy 1420 was developed in the form USSR as a lightweight, weldable, corrosion resistant alloy for aerospace applications. The alloy is primarily strengthened upon aging by the homogeneous precipitation of metastable [delta][prime] (Al[sub 3]Li). The equilibrium T-phase (Al[sub 2]MgLi) also precipitated during aging on grain boundaries and dislocations but does not contribute to strength and can have deleterious effects on fracture toughness. The addition of scandium, which refines the ingot grain structure, led to the evolution of alloy 1421 which exhibits higher strength and superior weldability compared to the earlier 1420 alloy. Zirconium is added to both alloys and forms a coherent precipitate, [beta][prime] (Al[sub 3]Zr), which acts as a recrystallization inhibitor. The fracture resistance of alloys 1420 and 1421 in the T6 temper has been examined by R-curve determination and the observed behavior has been compared with Al alloy, 2219-T87. The center-cracked (M(T)) sheet panels tested in this study were of sufficient width to produce stable crack growth to a [Delta]a of [approximately] 25 mm and the R-curves that were generated allowed for a comparison to be made of the stable crack growth resistance between the alloys in accordance with ASTM E561-86. The data presented are part of an extensive collaborative test program involving both private industry and government laboratories to evaluate the 1420 and 1421 alloys.

  15. Low-temperature electrical resistivity study of deformed Inconel alloy 600

    International Nuclear Information System (INIS)

    Chan, F.S.; Yao, Y.D.; Wang, S.H.

    2006-01-01

    The electrical resistivity of a plastic deformed Inconel alloy 600 (alloy of Ni 72 Cr 16 Fe 8) as function of temperature between 25 K and 300 K was studied. The deformation does not affect the Curie temperature much; it is roughly near 176 K of the deflected point at electrical resistivity, except for the sample with 75% deformation. The λ-type behavior of the electrical resistivity is a typical signal for the magnetic phase transition

  16. [The study of the colorimetric characteristics of the cobalt-chrome alloys abutments covered by four different all-ceramic crowns by using dental spectrophotometer].

    Science.gov (United States)

    Chen, Yifan; Liu, Hongchun; Meng, Yukun; Chao, Yonglie; Liu, Changhong

    2015-06-01

    This study aims to evaluate the optical data of the different sites of the cobalt-chrome (Co-Cr) alloy abutments covered by four different all-ceramic crowns and the color difference between the crowns and target tab using a digital dental spectrophotometer. Ten Co-Cr alloy abutments were made and tried in four different groups of all-ceramic crowns, namely, Procera aluminia, Procera zirconia, Lava zirconia (Lava-Zir), and IPS E.max glass-ceramic lithium disilicate-reinforced monolithic. The color data of the cervical, body, and incisal sites of the samples were recorded and analyzed by dental spectrophotometer. The CIE L*, a*, b* values were again measured after veneering. The color difference between the abutments covered by all-ceramic crowns and A2 dentine shade tab was evaluated. The L* and b* values of the abutments can be increased by all of the four groups of all-ceramic copings, but a* values were decreased in most groups. A statistical difference was observed among four groups. After being veneered, the L* values of all the copings declined slightly, and the values of a*, b* increased significantly. When compared with A2 dentine shade tab, the ΔE of the crowns was below 4. Four ceramic copings were demonstrated to promote the lightness and hue of the alloy abutments effecttively. Though the colorimetric baseline of these copings was uneven, veneer porcelain can efficiently decrease the color difference between the samples and thee target.

  17. Fe(II)-substituted cobalt ferrite nanoparticles against multidrug resistant microorganisms

    Science.gov (United States)

    Žalnėravičius, Rokas; Paškevičius, Algimantas; Mažeika, Kęstutis; Jagminas, Arūnas

    2018-03-01

    The present study is focused on the determination the influence of cobalt content in the magnetic cobalt ferrite nanoparticles (Nps) on their antibacterial efficiency against gram-negative Escherichia coli and gram-positive Staphylococcus aureus bacteria and several Candida species, in particular C. parapsilosis and C. albicans. For the synthesis of Fe(II) substituted cobalt ferrite Nps by co-precipitation way, the L-lysine was used as the capping biocompatible agent and the particle size was successfully controlled to be in the range of 5-6.4 nm. The antimicrobial efficiencies of the CoxFe1-xFe2O4@Lys Nps, where x varies from 0.2 to 1.0, were evaluated through the quantitative analysis by comparing with that of Fe3O4@Lys Nps and L-lysine. In this way, it was evidenced that increase in the Co2+ content in the similar sized cobalt ferrite Nps resulted in an increase in their antimicrobial potency into 93.1-86.3 % for eukaryotic and into 96.4-42.7 % for prokaryotic strains. For characterization the composition, structure, and morphology of the tested herein Nps inductively coupled plasma optical emission spectrometry, X-ray diffraction, high-resolution transmission electron microscopy, Mössbauer, and FTIR spectroscopy techniques were conferred.

  18. Corrosion resistance of metals and alloys in molten alkalies

    International Nuclear Information System (INIS)

    Zarubitskij, O.G.; Dmitruk, B.F.; Minets, L.A.

    1979-01-01

    Literature data on the corrosion of non-ferrous and noble metals, iron and steels in the molten alkalis and mixtures of their base are presented. It is shown that zirconium, niobium and tantalum are characterized by high corrosion stability in the molten NaOH. Additions of NaOH and KOH to the alkali chloride melts result in a 1000 time decrease of zirconium corrosion rate at 850 deg. The data testify to the characteristic passivating properties of OH - ions; Mo and W do not possess an ability to selfpassivation in hydroxide melts. Corrosion resistance of carbon and chromium-nickel steels in hydroxide melts depends considerably on the temperature, electrolyte composition and atmosphere over them. At the temperatures up to 600 deg C chromium-nickel steel is corrosion resistant in the molten alkali only in the inert atmosphere. Corrosion rate of chromium-nickel alloy is the lower the less chromium and the more nickel it contains. For the small installations the 4Kh18N25S2 and Kh23N28M3D3T steels can be recommended

  19. Novel Concepts for Damage-Resistant Alloys in Next Generation Nuclear Power Systems

    Energy Technology Data Exchange (ETDEWEB)

    Stephen M. Bruemmer; Peter L. Andersen; Gary Was

    2002-12-27

    The discovery of a damage-resistant alloy based on Hf solute additions to a low-carbon 316SS is the highlight of the Phase II research. This damage resistance is supported by characterization of radiation-induced microstructures and microchemistries along with measurements of environmental cracking. The addition of Hf to a low-carbon 316SS reduced the detrimental impact of radiation by changing the distribution of Hf. Pt additions reduced the impact of radiation on grain boundary segregation but did not alter its effect on microstructural damage development or cracking. Because cracking susceptibility is associated with several material characteristics, separate effect experiments exploring strength effects using non-irradiated stainless steels were conducted. These crack growth tests suggest that irradiation strength by itself can promote environmental cracking. The second concept for developing damage resistant alloys is the use of metastable precipitates to stabilize the microstructure during irradiation. Three alloys have been tailored for evaluation of precipitate stability influences on damage evolution. The first alloy is a Ni-base alloy (alloy 718) that has been characterized at low neutron irradiation doses but has not been characterized at high irradiation doses. The other two alloys are Fe-base alloys (PH 17-7 and PH 17-4) that have similar precipitate structures as alloy 718 but is more practical in nuclear structures because of the lower Ni content and hence lesser transmutation to He.

  20. [Study on corrosion resistance of three non-noble porcelain alloys].

    Science.gov (United States)

    Wu, Zhikai; Xu, Sheng; Li, Wei; Teng, Jin; Li, Ning

    2011-10-01

    To study the electrochemical corrosion behavior of Co-Cr, Ni-Cr and Ni-Cr-Be based porcelain alloys in NaCl solution. Five samples of each alloy were made respectively, electric polarization curve of each alloy was obtained using potentiodynamic polarization technique. Self-corrosion potential (E(corr)), self-corrosion current density (I(corr), passive region and transpassivation potential were tested. Microstructure and constituent was examined using scanning electron microscopy and energy dispersive spectroscopy. Co-Cr alloy possessed the most desirable corrosion resistance because of its integrated, homogeneous and compact passive film. The poor compactness of Ni-Cr alloy's passive film decreased its corrosion resistance. Ni-Cr-Be alloy exhibited the worst corrosion resistance due to the Cr and Mo depleted Ni-Be eutectic phases in the alloy. Taking biological security into consideration, it is necessary to avoid the application of porcelain alloys with Be element. Co-Cr alloy with better biocompatibility possesses much broader prospect in the field of dental restoration.

  1. Residual stresses in a surface remelting of castings made of cobalt alloy MAR-M509 with a plasma generated in electric arc

    Directory of Open Access Journals (Sweden)

    Z. Opiekun

    2010-01-01

    Full Text Available The manuscript presents the results of measurements of residual stresses (RS in partial meltings of casting surfaces made of cobalt alloy MAR-M509. The partial meltings were made with an argon plasma beam by GTAW method. The values of RS were deter-mined by X-ray diffraction method in grazing incident geometry, by g-sin2ψ method and in Bragg-Brentano (BB geometry. It has been stated that RS values depend on the parameters of partial melting process. It has been claimed that compressive stresses, which are present in the thin layer up to ca 2 μm, convert to tensile stresses in deeper layers of partial meltings.

  2. Cluster formula of Fe-containing Monel alloys with high corrosion-resistance

    Energy Technology Data Exchange (ETDEWEB)

    Li Baozeng; Gu Junjie [Key Lab of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Wang Qing, E-mail: wangq@dlut.edu.cn [Key Lab of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Ji Chunjun [College of Energy Source and Power, Dalian University of Science and Technology, Dalian, 116024 (China); Wang Yingmin; Qiang Jianbing [Key Lab of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China); Dong Chuang, E-mail: dong@dlut.edu.cn [Key Lab of Materials Modification by Laser, Ion and Electron Beams (Dalian University of Technology), Ministry of Education, School of Materials Science and Engineering, Dalian University of Technology, Dalian 116024 (China)

    2012-06-15

    The cluster-plus-glue-atom model is applied in the composition interpretation of Monel alloys. This model considers ideal atomic nearest neighbor configurations among the constituent elements and has been used in understanding compositions of complex alloys like quasicrystals, amorphous alloys, and cupronickels. According to this model, any structure can be expressed by cluster formula [cluster](glue atom){sub x}, x denoting the number of glue atoms matching one cluster. According to this model, two groups of experimental composition series [Fe{sub 1}Ni{sub 12}]Cu{sub x} and [Fe{sub y}Ni{sub 12}]Cu{sub 5} were designed which fell close to conventional Fe-containing Monel alloys. The designed alloys after solution treatment plus water quenching, are monolithic FCC Ni-based solid solutions. Among them, the [Fe{sub 1}Ni{sub 12}]Cu{sub 5} alloy has the highest corrosion resistance in simulated sea water, and its performance is superior to that of industrial Monel 400 alloy. - Highlights: Black-Right-Pointing-Pointer A stable solid solution model is proposed using our 'cluster-plus-glue-atom model'. Black-Right-Pointing-Pointer This model is used to develop Monel corrosion resistant alloys. Black-Right-Pointing-Pointer Single FCC structure is easily retained. Black-Right-Pointing-Pointer The alloys show good corrosion properties. Black-Right-Pointing-Pointer This work contributes to the general understanding of engineering alloys.

  3. The oxidation resistance and ignition temperature of AZ31 magnesium alloy with additions of La2O3 and La

    International Nuclear Information System (INIS)

    Zhao, Shizhe; Zhou, Hong; Zhou, Ti; Zhang, Zhihui; Lin, Pengyu; Ren, Luquan

    2013-01-01

    Highlights: ► Using lanthanum and lanthanum oxide (La 2 O 3 ) can improve oxidation resistance of magnesium alloy. ► La 2 O 3 is as effective as La in affecting both alloy microstructure and oxidation resistance. ► The optimum La concentration in alloy is ∼0.7 wt.%. ► We analyzed the oxidation kinetics of AZ31 alloy with both additions. - Abstract: We investigate the oxidation resistance of AZ31 magnesium alloy with additions of La and La oxide (La 2 O 3 ). The contributor is the practical La content in alloy. Both La and La 2 O 3 are effective in improving the oxidation resistance of Mg alloys. The samples with La content of ∼ 0.7 wt.% possess the best resistance to oxidation of all. Oxide scale, ignition temperature and oxidation kinetics are analyzed. However, higher La content is detrimental to the oxidation resistance.

  4. Structural heat-resistant β-NiAl + γ'-Ni3Al alloys of the Ni-Al-Co system: I. Solidification and structure

    Science.gov (United States)

    Povarova, K. B.; Drozdov, A. A.; Bazyleva, O. A.; Morozov, A. E.; Antonova, A. V.; Bondarenko, Yu. A.; Bulakhtina, M. A.; Ashmarin, A. A.; Arginbaeva, E. G.; Alad'ev, N. A.

    2017-09-01

    When analyzing the ternary Ni-Al- M phase diagrams, where M is a group VI-VIII transition metal, we chose the Ni-Al-Co system, where the γ' and γ phases are in equilibrium with the β phase, as a base for designing alloys with the following physicochemical properties: a moderate density (≤7.2 g/cm3) and satisfactory heat resistance at temperatures up to 1300°C. The structure formation in heterophase β + γ' alloys during directional solidification is studied. It is found that, in contrast to cobalt-free β + γ' alloys (where the γ'-Ni3Al aluminide forms according to the peritectic reaction L + β ⇄ γ'), the alloys with 8-10 at % Co studied in this work during directional solidification at 1370°C contain the degenerate eutectic L ⇄ β + γ. The transition from the β + γ field to the β + γ' + γ field occurs in the temperature range 1323-1334°C, and the γ' phase then forms according to the reaction β + γ ⇄ γ'.

  5. High Velocity Oxidation and Hot Corrosion Resistance of Some ODS Alloys

    Science.gov (United States)

    Lowell, C. E.; Deadmore, D. L.

    1977-01-01

    Several oxide dispersion strengthened (ODS) alloys were tested for cyclic, high velocity, oxidation, and hot corrosion resistance. These results were compared to the resistance of an advanced, NiCrAl coated superalloy. An ODS FeCrAl were identified as having sufficient oxidation and hot corrosion resistance to allow potential use in an aircraft gas turbine without coating.

  6. Effect of cold working on the stress corrosion cracking resistance of nickel-chromium-iron alloys

    International Nuclear Information System (INIS)

    Yonezawa, T.; Onimura, K.

    1987-01-01

    In order to grasp the stress corrosion cracking resistance of cold worked nickel base alloys in PWR primary water, the effect of cold working on the stress corrosion cracking resistance of alloys 600, X-750 and 690, in high temperature water, have been studied. Stress corrosion cracking tests were conducted at 360 0 C (633K) in a simulated PWR primary water for about 12,000 hours (43.2Ms). From the test results, it is concluded that the stress corrosion cracking resistance in the cold worked Alloy 600 at the same applied stress level increases with an increase in cold working ratio, and the cold worked alloys of thermally treated 690 and X-750 have excellent stress corrosion cracking resistance. (Author)

  7. High temperature corrosion resistance of candidate nickel-based weld overlay alloys in a low NOx environment

    Energy Technology Data Exchange (ETDEWEB)

    Deacon, R.M.; Du Pont, J.N.; Marder, A.R. [Lehigh University, Bethlehem, PA (United States)

    2007-07-15

    Changes in environmental regulations have led many fossil fuel-fired boiler operators to alter their combustion practices (low NOx, burning), thereby lowering plant emissions. This change has led to unacceptable wastage of carbon and low alloy steel waterwall tubes and expensive shutdowns due to severe corrosion. One favored solution is to weld overlay a more corrosion resistant alloy on top of existing tubes. Two nickel-based alloys developed for such applications were tested alongside the commercially available alloy 622 in a simulated low NOx, environment. Electron probe microanalysis (EPMA) examination of the weld overlays and corrosion scales demonstrated that microsegregation of molybdenum occurred in one of the candidate alloys and alloy 622. This microsegregation had a detrimental effect on the corrosion resistance of these alloys. The candidate alloy with higher chromium concentration, low nominal molybdenum concentration, and corresponding minimum molybdenum segregation, exhibited the best corrosion resistance of the examined alloys.

  8. High temperature corrosion resistance of candidate nickel-based weld overlay alloys in a low NO {sub x} environment

    Energy Technology Data Exchange (ETDEWEB)

    Deacon, R.M. [Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015 (United States)], E-mail: rmd3@lehigh.edu; DuPont, J.N. [Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015 (United States); Marder, A.R. [Lehigh University, 5 East Packer Avenue, Bethlehem, PA 18015 (United States)

    2007-07-15

    Changes in environmental regulations have led many fossil fuel-fired boiler operators to alter their combustion practices (low NO {sub x} burning), thereby lowering plant emissions. This change has led to unacceptable wastage of carbon and low alloy steel waterwall tubes and expensive shutdowns due to severe corrosion. One favored solution is to weld overlay a more corrosion resistant alloy on top of existing tubes. Two nickel-based alloys developed for such applications were tested alongside the commercially available alloy 622 in a simulated low NO {sub x} environment. Electron probe microanalysis (EPMA) examination of the weld overlays and corrosion scales demonstrated that microsegregation of molybdenum occurred in one of the candidate alloys and alloy 622. This microsegregation had a detrimental effect on the corrosion resistance of these alloys. The candidate alloy with higher chromium concentration, low nominal molybdenum concentration, and corresponding minimum molybdenum segregation, exhibited the best corrosion resistance of the examined alloys.

  9. High-temperature corrosion-resistant iron-aluminide (FeAl) alloys exhibiting improved weldability

    Science.gov (United States)

    Maziasz, Philip J.; Goodwin, Gene M.; Liu, Chain T.

    1996-01-01

    This invention relates to improved corrosion-resistant iron-aluminide intermetallic alloys. The alloys of this invention comprise, in atomic percent, from about 30% to about 40% aluminum alloyed with from about 0.1% to about 0.5% carbon, no more than about 0.04% boron such that the atomic weight ratio of boron to carbon in the alloy is in the range of from about 0.01:1 to about 0.08:1, from about 0.01 to about 3.5% of one or more transition metals selected from Group IVB, VB, and VIB elements and the balance iron wherein the alloy exhibits improved resistance to hot cracking during welding.

  10. Thermo-physical Properties and Mechanical Properties of Burn-resistant Titanium Alloy Ti40

    Directory of Open Access Journals (Sweden)

    LAI Yunjin

    2017-10-01

    Full Text Available As a functional material of burn-resistant titanium alloy, the physical properties of Ti40 alloy were first reported. The chemical compositions of Ti40 alloy ingots by VAR were uniform. The microstructures of Ti40 alloy slab manufactured by HEFF+WPF were uniform. The results show that the room temperature tensile strength of Ti40 alloy is 950 MPa degree. The properties of high temperature heat exposure, creep resistance and lasting time are good at 500 ℃. In the range from room temperature to 600 ℃, Young's modulus and shear modulus are decreased linearly with increasing the temperature, Poisson's ratio is increases slowly as the temperature rises, and linear thermal expansion coefficient and average linear expansion coefficient is increase as the temperature rises.

  11. Alloying effects on the high-temperature oxidation resistance of Cr-Cr{sub 2}Nb

    Energy Technology Data Exchange (ETDEWEB)

    Tortorelli, P.F.; DeVan, J.H.

    1994-09-01

    Alloying effects on the high-temperature oxidation resistance of Cr-Cr{sub 2}Nb were examined on the basis of isothermal exposures to air at 950 C. Additions of either Re and Al or Fe, Ni, and Al had relatively little effect on weight gains relative to the Cr-6% Nb binary alloy. One alloying element that improved the mechanical behavior of Cr-Cr{sub 2}Nb alloys substantially increased the oxidation rates and spallation susceptibilities of Cr-6 and -12% Nb alloys. However, the addition of another element completely offset these deleterious effects. The presence of this latter element resulted in the best overall oxidation behavior (in terms of both weight gains and spallation tendencies) of all Cr-Cr{sub 2}Nb compositions. Its beneficial effect can be attributed to improvement in the oxidation resistance of the Cr-rich phase.

  12. Advanced Testing Techniques to Measure the PWSCC Resistance of Alloy 690 and its Weld Metals

    Energy Technology Data Exchange (ETDEWEB)

    P.Andreson

    2004-10-01

    Wrought Alloy 600 and its weld metals (Alloy 182 and Alloy 82) were originally used in pressurized water reactors (PWRs) due to the material's inherent resistance to general corrosion in a number of aggressive environments and because of a coefficient of thermal expansion that is very close to that of low alloy and carbon steel. Over the last thirty years, stress corrosion cracking in PWR primary water (PWSCC) has been observed in numerous Alloy 600 component items and associated welds, sometimes after relatively long incubation times. The occurrence of PWSCC has been responsible for significant downtime and replacement power costs. As part of an ongoing, comprehensive program involving utilities, reactor vendors and engineering/research organizations, this report will help to ensure that corrosion degradation of nickel-base alloys does not limit service life and that full benefit can be obtained from improved designs for both replacement components and new reactors.

  13. Influence of Carbon and Nitrogen on Corrosion Resistance of High Purity Fe-50mass % Cr Alloy

    OpenAIRE

    Kato, Y.; Ujiro, T.; Satoh, S.; Yamato, K.; Abiko, K.

    1995-01-01

    High purity Fe-50mass%Cr alloys containing (C+N) in the range of 30 to 500 mass ppm were prepared and their corrosion resistance was investigated. Pitting potential in a 3.5mass%NaCl solution at 343K rose with reducing (C+N) content. Alloys containing (C+N) at less than 100 mass ppm did not sustain pitting corrosion. However, alloys containing 500 mass ppm (C+N) corroded severely in 6%FeCl3+1/20N HCl solutions. Heat treatment at 923K was recognized as influencing corrosion resistance due to p...

  14. Determination of emissivity coefficient of heat-resistant super alloys and cemented carbide

    Directory of Open Access Journals (Sweden)

    Kieruj Piotr

    2016-12-01

    Full Text Available This paper presents the analysis of emissivity engineering materials according to temperature. Experiment is concerned on difficult to machine materials, which may be turned with laser assisting. Cylindrical samples made of nickel-based alloys Inconel 625, Inconel 718, Waspaloy and tungsten-carbides based on cobalt matrix were analyzed. The samples’ temperature in contact method was compared to the temperature measured by non-contact pyrometers. Based on this relative, the value of the emissivity coefficient was adjusted to the right indication of pyrometers.

  15. Oxidation and corrosion resistance of candidate Stirling engine heater-head-tube alloys

    Science.gov (United States)

    Stephens, J. R.; Barrett, C. A.

    1984-01-01

    Sixteen candidate iron base Stirling engine heater head tube alloys are evaluated in a diesel fuel fired simulator materials test rig to determine their oxidation and corrosion resistance. Sheet specimens are tested at 820 C for 3500 hr in 5 hr heating cycles. Specific weight change data and an attack parameter are used to categorize the alloys into four groups; 10 alloys show excellent for good oxidation and corrosion resistance and six alloys exhibit poor or catastrophic resistance. Metallographic, X-ray, and electron microprobe analyses aid in further characterizing the oxidation and corrosion behavior of the alloys. Alloy compositions, expecially the reactive elements aluminum, titanium, and chromium, play a major role in the excellent oxidation and corrosion behavior of the alloys. The best oxidation resistance is associated with the formation of an iron nickel aluminum outer oxide scale, an intermediate oxide scale rich in chromium and titanium, and an aluminum outer oxide scale adjacent to the metallic substrate, which exhibits a zone of internal oxidation of aluminum and to some extent titanium.

  16. Corrosion resistance of aluminum-magnesium alloys in glacial acetic acid

    International Nuclear Information System (INIS)

    Zaitseva, L.V.; Romaniv, V.I.

    1984-01-01

    Vessels for the storage and conveyance of glacial acetic acid are produced from ADO and AD1 aluminum, which are distinguished by corrosion resistance, weldability and workability in the hot and cold conditions but have low tensile strength. Aluminum-magnesium alloys are stronger materials close in corrosion resistance to technical purity aluminum. An investigation was made of the basic alloying components on the corrosion resistance of these alloys in glacial acetic acid. Both the base metal and the weld joints were tested. With an increase in temperature the corrosion rate of all of the tested materials increases by tens of times. The metals with higher magnesium content show more pitting damage. The relationship of the corrosion resistance of the alloys to magnesium content is confirmed by the similar intensity of failure of the joint metal of all of the investigated alloys and by electrochemical investigations. The data shows that AMg3 alloy is close to technically pure ADO aluminum. However, the susceptibility of even this material to local corrosion eliminates the possibility of the use of aluminum-magnesium alloys as reliable constructional materials in glacial acetic acid

  17. Cooperative effect of silicon and other alloying elements on creep resistance of titanium alloys: insight from first-principles calculations.

    Science.gov (United States)

    Li, Yang; Chen, Yue; Liu, Jian-Rong; Hu, Qing-Miao; Yang, Rui

    2016-07-28

    Creep resistance is one of the key properties of titanium (Ti) alloys for high temperature applications such as in aero engines and gas turbines. It has been widely recognized that moderate addition of Si, especially when added together with some other elements (X), e.g., Mo, significantly improves the creep resistance of Ti alloys. To provide some fundamental understandings on such a cooperative effect, the interactions between Si and X in both hexagonal close-packed α and body-centered cubic β phases are systematically investigated by using a first-principles method. We show that the transition metal (TM) atoms with the number of d electrons (Nd) from 3 to 7 are attractive to Si in α phase whereas those with Nd > 8 and simple metal (SM) alloying atoms are repulsive to Si. All the alloying atoms repel Si in the β phase except for the ones with fewer d electrons than Ti. The electronic structure origin underlying the Si-X interaction is discussed based on the calculated electronic density of states and Bader charge. Our calculations suggest that the beneficial X-Si cooperative effect on the creep resistance is attributable to the strong X-Si attraction.

  18. Influence of casting procedures on the corrosion resistance of clinical dental alloys containing palladium.

    Science.gov (United States)

    Viennot, Stéphane; Lissac, Michèle; Malquarti, Guillaume; Dalard, Francis; Grosgogeat, Brigitte

    2006-05-01

    The aim of this study was to compare the in vitro corrosion resistance in artificial saliva of two palladium-silver alloys (a Pd-Ag (Pors on 4) and an Ag-Pd (Palliag LTG)), with and without casting defects; 1 nickel-chrome alloy and 1 high-gold alloy, cast under recommended conditions, served as controls. For each of the palladium-based alloys, three specimens corresponding to three different casting conditions were used: under recommended conditions, with the use of a graphite-containing investment and crucible, and by reusing the sprues and sprue button. The electrochemical tests were run in Fusayama-Meyer artificial saliva. The open-circuit potential was recorded in mV/SCE at t=24h. Then, potentiodynamic polarization was performed to measure the polarization resistance (R(p)) in kOmega cm(2) and the corrosion current (i(corr)) in microA cm(-2). Data were evaluated with one-way analysis of variance and multiple comparisons test (alpha=0.05). In addition, each specimen was examined by scanning electron microscopy. Compared to the control alloys, the electrochemical experiments in artificial saliva indicated satisfactory corrosion resistance for the Pd-Ag and Ag-Pd alloys; these results are related to their high noble metal content and stable substructure. The Pd-Ag alloy displayed superior electrochemical properties to those of the Ag-Pd alloy regardless of the casting condition. The use of the graphite-containing crucible and investment during the cast process did not dramatically reduce the corrosion resistance values, but the reuse of sprues and the sprue button did. The optimal corrosion resistance values were obtained for the alloys cast according to the recommended conditions.

  19. Microstructure, tensile deformation mode and crevice corrosion resistance in Ti-10Mo-xFe alloys

    International Nuclear Information System (INIS)

    Min, X.H.; Emura, S.; Nishimura, T.; Tsuchiya, K.; Tsuzaki, K.

    2010-01-01

    The microstructure, the tensile deformation mode at ambient temperature and the crevice corrosion resistance at a high temperature of 373 K were investigated in the Ti-10Mo-xFe (x = 0, 1, 3, 5) alloys. The stability of the β phase increased, and the formation of the α'' martensite and the athermal ω phase was suppressed by the increase in the Fe content. EPMA examinations indicated that the existence of the α'' martensite in the Ti-10Mo alloy was caused by the solidification segregation of Mo atoms. EBSD observations showed that the deformation mode changed from a {3 3 2} twinning to a slip by an increase in the Fe content, which coincided with the prediction by the electron/atom (e/a) ratio. The Ti-10Mo-3Fe alloy showed the highest yield strength of 935 MPa among all the alloys, while the Ti-10Mo-1Fe alloy showed the lowest value of 563 MPa due to the change in the deformation mode. On the other hand, all the alloys exhibited a high crevice corrosion resistance in a high chloride and high acidic solution at the high temperature, although the corrosion resistance decreased with an increase in the Fe content. The decrease in the corrosion resistance can be explained by the bond order (Bo). A good combination of tensile properties and crevice corrosion resistance may be obtainable through a further optimization of the Fe content by the e/a ratio and the Bo.

  20. The metallurgy of high temperature alloys

    Science.gov (United States)

    Tien, J. K.; Purushothaman, S.

    1976-01-01

    Nickel-base, cobalt-base, and high nickel and chromium iron-base alloys are dissected, and their microstructural and chemical components are assessed with respect to the various functions expected of high temperature structural materials. These functions include the maintenance of mechanical integrity over the strain-rate spectrum from creep resistance through fatigue crack growth resistance, and such alloy stability expectations as microstructural coarsening resistance, phase instability resistance and oxidation and corrosion resistance. Special attention will be given to the perennial conflict and trade-off between strength, ductility and corrosion and oxidation resistance. The newest developments in the constitution of high temperature alloys will also be discussed, including aspects relating to materials conservation.

  1. Cast iron-base alloy for cylinder/regenerator housing

    Science.gov (United States)

    Witter, Stewart L.; Simmons, Harold E.; Woulds, Michael J.

    1985-01-01

    NASACC-1 is a castable iron-base alloy designed to replace the costly and strategic cobalt-base X-40 alloy used in the automotive Stirling engine cylinder/generator housing. Over 40 alloy compositions were evaluated using investment cast test bars for stress-rupture testing. Also, hydrogen compatibility and oxygen corrosion resistance tests were used to determine the optimal alloy. NASACC-1 alloy was characterized using elevated and room temperature tensile, creep-rupture, low cycle fatigue, heat capacity, specific heat, and thermal expansion testing. Furthermore, phase analysis was performed on samples with several heat treated conditions. The properties are very encouraging. NASACC-1 alloy shows stress-rupture and low cycle fatigue properties equivalent to X-40. The oxidation resistance surpassed the program goal while maintaining acceptable resistance to hydrogen exposure. The welding, brazing, and casting characteristics are excellent. Finally, the cost of NASACC-1 is significantly lower than that of X-40.

  2. Proceedings of the sixth international workshop on rare earth-cobalt permanent magnets and their applications, August 31 - September 2, 1982, and third international symposium on magnetic anisotropy and coercivity in rare earth-transition metal alloys, September 3, 1982

    International Nuclear Information System (INIS)

    Fidler, J.

    1982-01-01

    The first part (workshop) is concerned specifically with applications of rare earth-cobalt permanent magnets. The session headings are 1) electro-mechanical applications 2) electronic and miscellaneous applications 3) magneto-mechanical applications plus workshop on measurement methods 4) new materials and processes 5) industrial applications of REPM and future aspects. The second part (symposium) is concerned with physical properties of specific rare earth-transition metal alloys. (G.Q.)

  3. Microstructural Changes during High Temperature Service of a Cobalt-Based Superalloy First Stage Nozzle

    OpenAIRE

    Luna Ramírez, A.; Porcayo-Calderon, J.; Mazur, Z.; Salinas-Bravo, V. M.; Martinez-Gomez, L.

    2016-01-01

    Superalloys are a group of alloys based on nickel, iron, or cobalt, which are used to operate at high temperatures (T > 540°C) and in situations involving very high stresses like in gas turbines, particularly in the manufacture of blades, nozzles, combustors, and discs. Besides keeping its high resistance to temperatures which may approach 85% of their melting temperature, these materials have excellent corrosion resistance and oxidation. However, after long service, these components undergo ...

  4. Progress with alloy 33 (UNS R20033), a new corrosion resistant chromium-based austenitic material

    International Nuclear Information System (INIS)

    Koehler, M.; Heubner, U.; Eichenhofer, K.W.; Renner, M.

    1996-01-01

    Alloy 33 (UNS R20033), a new chromium-based corrosion resistant austenitic material with nominally (wt. %) 33 Cr, 32 Fe, 31 Ni, 1.6 Mo, 0.6 Cu, 0.4 N has been introduced to the market in 1995. This paper provides new data on this alloy with respect to mechanical properties, formability, weldability, sensitization characteristics and corrosion behavior. Mechanical properties of weldments including ductility have been established, and match well with those of wrought plate material, without any degradation of ISO V-notch impact toughness in the heat affected zone. When aged up to 8 hours between 600 C and 1,000 C the alloy is not sensitized when tested in boiling azeotropic nitric acid (Huey test). Under field test conditions alloy 33 shows excellent resistance to corrosion in flowing 96--98.5% H 2 SO 4 at 135 C--140 C and flowing 99.1% H 2 SO 4 at 150 C. Alloy 33 has also been tested with some success in 96% H 2 SO 4 with nitrosyl additions at 240 C. In nitric acid alloy 33 is corrosion resistant up to 85% HNO 3 and 75 C or even more. Alloy 33 is also corrosion resistant in 1 mol. HCl at 40 C and in NaOH/NaOCl-solutions. In artificial seawater the pitting potential remains unchanged up to 75 C and is still well above the seawater's redox potential at 95 C. Alloy 33 can be easily manufactured into all product forms required. The new data provided support the multipurpose character of alloy 33 to cope successfully with many requirements of the Chemical Process Industry, the Oil and Gas Industry and the Refinery Industry

  5. Corrosion resistance of Ni-Cr-Mo alloys. Chemical composition and metallurgical condition's effects

    International Nuclear Information System (INIS)

    Zadorozne, N.S.; Rebak, Raul B.

    2009-01-01

    Ni-Cr-Mo alloys offer an outstanding corrosion resistance in a wide variety of highly-corrosive environments. This versatility is due to the excellent performance of nickel in hot alkaline solutions and the beneficial effect of chromium and molybdenum in oxidizing and reducing conditions, respectively. Alloy C-22 (22 % Cr-13 % Mo-3% W) is a well known versatile member of this family. Due to its excellent corrosion resistance in a wide variety of environments, Alloy C-22 has been selected for the fabrication of the corrosion-resistant outer shell of the high-level nuclear waste container. The increasing demand of the industry for corrosion resistant alloys with particular properties of corrosion and mechanical resistance has led to the development of new alloys. Alloy C-22HS (Ni-21 % Cr-17 % Mo) is a new high-strength corrosion resistant material recently developed and introduced into the market. This alloy provides a corrosion resistance comparable with that of other C-type alloys, and it can also be age hardened to effectively double its yield strength. HASTELLOY HYBRID-BC1 (Ni-22 % Mo-15 % Cr) is a new development intended for filling the gap between Ni-Mo and Ni-Cr-Mo alloys. This novel alloy is able to withstand HCl and H 2 SO 4 , even in the presence of dissolved oxygen and other oxidizing species. Its resistance to chloride-induced pitting corrosion, crevice corrosion and stress corrosion cracking is also remarkable. Thermal aging of Ni-Cr-Mo alloys leads to microstructure changes depending on the temperature range and exposure time at temperature. A Long Range Ordering (LRO) reaction can occur in the range of 350 C degrees to 600 C degrees, producing an ordered Ni 2 (Cr,Mo) phase. This ordering reaction does not seem to affect the corrosion resistance and produces only a slight loss in ductility. LRO transformation is homogeneous and has proven to be useful to fabricate the age-hard enable Alloy C22-HS. Tetrahedral Close Packed (TCP) phases, like μ, σ and

  6. Corrosion resistant Zn–Co alloy coatings deposited using saw-tooth ...

    Indian Academy of Sciences (India)

    Optimal configuration, represented as (Zn–Co)2.0/4.0/300 was found to exhibit ∼ 89 times better corrosion resistance compared to monolithic (Zn–Co)3.0 alloy deposited for same time, from same bath. The better corrosion resistance of CMMA coatings was attributed to changed interfacial dielectric properties, evidenced by ...

  7. Critical behavior of electrical resistivity in amorphous Fe–Zr alloys

    Indian Academy of Sciences (India)

    Electrical resistivity (ρ) of the amorphous (a-)Fe100-Zr ( = 8.5, 9.5 and 10) alloys has been measured in the temperature range 77 to 300 K, which embraces the second-order magnetic phase transition at the Curie temperature point . Analysis of the resistivity data particularly in the critical region reveals that these ...

  8. Effects of Pulse Electromagnetic Field on Corrosion Resistance of Al-5 % Cu Alloy

    Science.gov (United States)

    Wang, B.; Tang, L. D.; Qi, J. G.; Wang, J. Z.

    2013-03-01

    It was investigated that corrosion resistance of Al-5 % Cu alloy was influenced by pulse electromagnetic field (PEMF). The morphologies were observed by scanning election microscopy (SEM). The corrosion behaviors were investigated by potentiodynamic polarization tests and immersion tests. The results indicated that corrosion resistance of samples could be increased by using pulse electromagnetic field, moreover, the optimum parameter of pulse electromagnetic field in this experiment was showed as follows: 500 V, 3 Hz, 30 s. Decreasing the quantity of eutectic in grain boundaries and refining the grains were main causations for increasing corrosion resistance of Al-5 % Cu alloy with pulse electromagnetic field.

  9. Cobalt Chloride Induces Expression and Function of Breast Cancer Resistance Protein (BCRP/ABCG2) in Human Renal Proximal Tubular Epithelial Cell Line HK-2.

    Science.gov (United States)

    Nishihashi, Katsuki; Kawashima, Kei; Nomura, Takami; Urakami-Takebayashi, Yumiko; Miyazaki, Makoto; Takano, Mikihisa; Nagai, Junya

    2017-01-01

    The human breast cancer resistance protein (BCRP/ABCG2), a member of the ATP-binding cassette transporter family, is a drug transporter restricting absorption and enhancing excretion of many compounds including anticancer drugs. The cis-regulatory elements in the BCRP promoter include a hypoxia response element, i.e., the DNA binding site for hypoxia-inducible factor-1 (HIF-1). In this study, we investigated the effect of cobalt chloride, a chemical inducer of HIF-1α, on the expression and function of BCRP in human renal proximal tubular cell line HK-2. Cobalt chloride treatment significantly increased the mRNA expression of not only glucose transporter 1 (GLUT1), a typical HIF-1 target gene mRNA, but also ABCG2 mRNA in HK-2 cells. The BCRP inhibitor Ko143-sensitive accumulation of BCRP substrates such as Hoechst33342 and mitoxantrone was significantly enhanced by cobalt chloride treatment. In addition, treatment with cobalt chloride significantly increased the Ko143-sensitive accumulation of fluorescein isothiocyanate-labeled methotrexate in HK-2 cells. Furthermore, cobalt chloride treatment attenuated the cytotoxicity induced by mitoxantrone and methotrexate, which might be, at least in part, due to the increase in BCRP-mediated transport activity via HIF-1 activation. These findings indicate that HIF-1 activation protects renal proximal tubular cells against BCRP substrate-induced cytotoxicity by enhancing the expression and function of BCRP in renal proximal tubular cells.

  10. Influence of carbon and nitrogen on corrosion resistance of high purity Fe-50mass% Cr alloys

    International Nuclear Information System (INIS)

    Kato, Y.; Ujiro, T.; Satoh, S.; Yamato, K.; Abiko, K.

    1995-01-01

    High purity Fe-50mass%Cr alloys containing (C+N) in the range of 30 to 500 mass ppm were prepared and their corrosion resistance was investigated. Pitting potential in a 3.5mass%NaCl solution at 343K rose with reducing (C+N) content. Alloys containing (C+N) at less than 100 mass ppm did not sustain pitting corrosion. However, alloys containing 500 mass ppm (C+N) corroded severely in 6%FeCl 3 +1/20N HCl solutions. Heat treatment at 923K was recognized as influencing corrosion resistance due to precipitation of carbonitrides only in the case of the alloy containing 500 mass ppm (C+N). (orig.)

  11. Cobalt: A vital element in the aircraft engine industry

    Science.gov (United States)

    Stephens, J. R.

    1981-01-01

    Recent trends in the United States consumption of cobalt indicate that superalloys for aircraft engine manufacture require increasing amounts of this strategic element. Superalloys consume a lion's share of total U.S. cobalt usage which was about 16 million pounds in 1980. In excess of 90 percent of the cobalt used in this country was imported, principally from the African countries of Zaire and Zambia. Early studies on the roles of cobalt as an alloying element in high temperature alloys concentrated on the simple Ni-Cr and Nimonic alloy series. The role of cobalt in current complex nickel base superalloys is not well defined and indeed, the need for the high concentration of cobalt in widely used nickel base superalloys is not firmly established. The current cobalt situation is reviewed as it applies to superalloys and the opportunities for research to reduce the consumption of cobalt in the aircraft engine industry are described.

  12. Effects of V addition on recrystallization resistance of 7150 aluminum alloy after simulative hot deformation

    Energy Technology Data Exchange (ETDEWEB)

    Lai, Jing; Shi, Cangji; Chen, X.-Grant, E-mail: xgrant_chen@uqac.ca

    2014-10-15

    The effects of different V contents (0.01 to 0.19 wt.%) on the recrystallization resistance of 7150 aluminum alloys during post-deformation heat treatment were investigated. The microstructural evolutions at as-cast, as-homogenized conditions and after post-deformation annealing were studied using optical, scanning electron and transmission electron microscopes and using the electron backscattered diffraction technique. The precipitation of Al{sub 21}V{sub 2} dispersoids was observed in alloys containing 0.11 to 0.19 wt.% V after homogenization. The dispersoids were mainly distributed in the dendrite cells, and the precipitate-free zones occurred in the interdendritic regions and near grain boundaries. V addition could significantly enhance the recrystallization resistance during post-deformation annealing, particularly in the presence of a great number of Al{sub 21}V{sub 2} dispersoids. Recrystallized grain growth was effectively restricted because of the dispersoid pinning effect. The alloy containing 0.15 wt.% V exhibited the highest recrystallization resistance amongst all V-containing alloys studied. - Highlights: • Investigated the effect of V level on microstructure and flow stress of 7150 alloys • Characterized microstructures using optical microscopy, SEM, TEM and EBSD • Described the precipitation behavior of V-dispersoids in the dendritic structure • Studied the V effect on recrystallization resistance during post heat treatment • V addition greatly enhanced the recrystallization resistance during annealing.

  13. Corrosion resistance and microstructure characterization of rare-earth-transition metal-aluminum-magnesium alloys

    International Nuclear Information System (INIS)

    Banczek, E.P.; Zarpelon, L.M.C.; Faria, R.N.; Costa, I.

    2009-01-01

    This paper reports the results of investigation carried out to evaluate the corrosion resistance and microstructure of some cast alloys represented by the general formula: La 0.7-x Pr x Mg 0.3 Al 0.3 Mn 0.4 Co 0.5 Ni 3.8 (x = 0, 0.1, 0.3, 0.5, and 0.7). Scanning electron microscopy (SEM) and electrochemical methods, specifically, polarization curves and electrochemical impedance spectroscopy (EIS), have been employed in this study. The effects of Pr substitution on the composition of the various phases in the alloys and their corrosion resistance have been studied. The electrochemical results showed that the alloy without Pr and the one with total La substitution showed the highest corrosion resistance among the studied alloys. The corrosion resistance of the alloys decreased when Pr was present in the lowest concentrations (0.1 and 0.3), but for higher Pr concentrations (0.5 and 0.7), the corrosion resistance increased. Corrosion occurred preferentially in a Mg-rich phase.

  14. Advanced Corrosion-Resistant Zr Alloys for High Burnup and Generation IV Applications

    International Nuclear Information System (INIS)

    Arthur Motta; Yong Hwan Jeong; R.J. Comstock; G.S. Was; Y.S. Kim

    2006-01-01

    The objective of this collaboration between four institutions in the US and Korea is to demonstrate a technical basis for the improvement of the corrosion resistance of zirconium-based alloys in more extreme operating environments (such as those present in severe fuel duty, cycles high burnup, boiling, aggressive chemistry) and to investigate the feasibility (from the point of view of corrosion rate) of using advanced zirconium-based alloys in a supercritical water environment

  15. New oxidation-resistant tungsten alloys for use in the nuclear fusion reactors

    Science.gov (United States)

    Litnovsky, A.; Wegener, T.; Klein, F.; Linsmeier, Ch; Rasinski, M.; Kreter, A.; Tan, X.; Schmitz, J.; Coenen, J. W.; Mao, Y.; Gonzalez-Julian, J.; Bram, M.

    2017-12-01

    Smart tungsten-based alloys are under development as plasma-facing components for a future fusion power plant. Smart alloys are planned to adjust their properties depending on environmental conditions: acting as a sputter-resistant plasma-facing material during plasma operation and suppressing the sublimation of radioactive tungsten oxide in case of an accident on the power plant. New smart alloys containing yttrium are presently in the focus of research. Thin film smart alloys are featuring an remarkable 105-fold suppression of mass increase due to an oxidation as compared to that of pure tungsten at 1000 °C. Newly developed bulk smart tungsten alloys feature even better oxidation resistance compared to that of thin films. First plasma test of smart alloys under DEMO-relevant conditions revealed the same mass removal as for pure tungsten due to sputtering by plasma ions. Exposed smart alloy samples demonstrate the superior oxidation performance as compared to tungsten-chromium-titanium systems developed earlier.

  16. Enhanced antimicrobial properties, cytocompatibility, and corrosion resistance of plasma-modified biodegradable magnesium alloys.

    Science.gov (United States)

    Zhao, Ying; Jamesh, Mohammed Ibrahim; Li, Wing Kan; Wu, Guosong; Wang, Chenxi; Zheng, Yufeng; Yeung, Kelvin W K; Chu, Paul K

    2014-01-01

    Magnesium alloys are potential biodegradable materials and have received increasing attention due to their outstanding biological performance and mechanical properties. However, rapid degradation in the physiological environment and potential toxicity limit clinical applications. Recently, special magnesium-calcium (Mg-Ca) and magnesium-strontium (Mg-Sr) alloys with biocompatible chemical compositions have been reported, but the rapid degradation still does not meet clinical requirements. In order to improve the corrosion resistance, a rough, hydrophobic and ZrO(2)-containing surface film is fabricated on Mg-Ca and Mg-Sr alloys by dual zirconium and oxygen ion implantation. Weight loss measurements and electrochemical corrosion tests show that the corrosion rate of the Mg-Ca and Mg-Sr alloys is reduced appreciably after surface treatment. A systematic investigation of the in vitro cellular response and antibacterial capability of the modified binary magnesium alloys is performed. The amounts of adherent bacteria on the Zr-O-implanted and Zr-implanted samples diminish remarkably compared to the unimplanted control. In addition, significantly enhanced cell adhesion and proliferation are observed from the Zr-O-implanted sample. The results suggest that dual zirconium and oxygen ion implantation, which effectively enhances the corrosion resistance, in vitro biocompatibility and antimicrobial properties of Mg-Ca and Mg-Sr alloys, provides a simple and practical means to expedite clinical acceptance of biodegradable magnesium alloys. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  17. Factors Affecting the Hydrogen Environment Assisted Cracking Resistance of an AL-Zn-Mg-(Cu) Alloy

    Energy Technology Data Exchange (ETDEWEB)

    Young, G A; Scully, J R

    2002-04-09

    Precipitation hardenable Al-Zn-Mg alloys are susceptible to hydrogen environment assisted cracking (HEAC) when exposed to aqueous environments. In Al-Zn-Mg-Cu alloys, overaged tempers are used to increase HEAC resistance at the expense of strength but overaging has little benefit in low copper alloys. However, the mechanism or mechanisms by which overaging imparts HEAC resistance is poorly understood. The present research investigated hydrogen uptake, diffusion, and crack growth rate in 90% relative humidity (RH) air for both a commercial copper bearing Al-Zn-Mg-Cu alloy (AA 7050) and a low copper variant of this alloy in order to better understand the factors which affect HEAC resistance. Experimental methods used to evaluate hydrogen concentrations local to a surface and near a crack tip include nuclear reaction analysis (NRA), focused ion beam, secondary ion mass spectroscopy (FIB/SIMS) and thermal desorption spectroscopy (TDS). Results show that overaging the copper bearing alloys both inhibits hydrogen ingress from oxide covered surfaces and decreases the apparent hydrogen diffusion rates in the metal.

  18. Alloy 31, a new 6 moly stainless steel with improved corrosion resistance in seawater

    Energy Technology Data Exchange (ETDEWEB)

    Jasner, M.; Heubner, U. [Krupp VDM GmbH, Werdohl (Germany)

    1995-10-01

    Alloy 31--UNS N08031--31Ni-27Cr-6.5Mo-1.2Cu-0.2N-balance iron--is an advanced 6 Mo stainless steel with increased chromium and nickel, contents for seawater service. In hot seawater the pitting potential of alloy 31 remains high up to 90 C (194 F). Investigations of resistance to crevice corrosion in real piping systems in natural seawater, both North Sea and Baltic Sea, show that the threshold conditions for alloy 31 in chlorinated seawater (North Sea) are at 40 C and 1 ppm chlorine well superior to the 6 Mo stainless grades being currently in use. In addition, alloy 31 shows an excellent resistance to corrosion versus both hot reducing media (e.g. H{sub 2}SO{sub 4}) and hot oxidizing media (e.g. HNO{sub 3}). The combination of high resistance to localized corrosion vs. hot chloride-bearing cooling waters including seawater and aggressive oxidizing and reducing hot corrosive media is a unique feature of alloy 31. Alloy 31 is recommended for the construction of heat exchangers, process coolers and piping systems. The material is supplied in a number of semifinished products such as seamless and welded pipes, fittings, flanges, forged bars, plate, sheet, strip, wire and prefabricated piping systems.

  19. Creep fatigue of low-cobalt superalloys: Waspalloy, PM U 700 and wrought U 700

    Science.gov (United States)

    Leis, B. N.; Rungta, R.; Hopper, A. T.

    1983-01-01

    The influence of cobalt content on the high temperature creep fatigue crack initiation resistance of three primary alloys was evaluated. These were Waspalloy, Powder U 700, and Cast U 700, with cobalt contents ranging from 0 up to 17 percent. Waspalloy was studied at 538 C whereas the U 700 was studied at 760 C. Constraints of the program required investigation at a single strain range using diametral strain control. The approach was phenomenological, using standard low cycle fatigue tests involving continuous cycling tension hold cycling, compression hold cycling, and symmetric hold cycling. Cycling in the absence of or between holds was done at 0.5 Hz, whereas holds when introduced lasted 1 minute. The plan was to allocate two specimens to the continuous cycling, and one specimen to each of the hold time conditions. Data was taken to document the nature of the cracking process, the deformation response, and the resistance to cyclic loading to the formation of small cracks and to specimen separation. The influence of cobalt content on creep fatigue resistance was not judged to be very significant based on the results generated. Specific conclusions were that the hold time history dependence of the resistance is as significant as the influence of cobalt content and increased cobalt content does not produce increased creep fatigue resistance on a one to one basis.

  20. Hot corrosion resistance of a Pb-Sb alloy for lead acid battery grids

    Energy Technology Data Exchange (ETDEWEB)

    Osorio, Wislei R.; Garcia, Amauri [Department of Materials Engineering, University of Campinas - UNICAMP, PO Box 6122, 13083-970 Campinas, SP (Brazil); Aoki, Claudia S.C. [Research and Development Centre - CPqD Foundation, Rod. Campinas/Mogi, km 118.5, 13086-912 Campinas, SP (Brazil)

    2008-12-01

    The aim of this study was to evaluate the effects of the microstructural morphologies of a Pb-6.6 wt%Sb alloy on the resulting corrosion resistance in a 0.5 M H{sub 2}SO{sub 4} solution at different temperatures: environment temperature, 50 C and 70 C. A water-cooled unidirectional solidification system was employed permitting a wide range of microstructures to be analyzed. Electrochemical impedance spectroscopy (EIS) diagrams, potentiodynamic polarization curves and an equivalent circuit analysis were used to evaluate the corrosion behavior of the Pb-Sb alloy samples. It was found that with increasing temperatures the general corrosion resistance of Pb-Sb dendritic alloys decreases, and that independently of the working temperature finer dendritic spacings exhibit better corrosion resistance than coarser ones. (author)

  1. Mechanical properties and oxidation and corrosion resistance of reduced-chromium 304 stainless steel alloys

    Science.gov (United States)

    Stephens, J. R.; Barrett, C. A.; Gyorgak, C. A.

    1979-01-01

    An experimental program was undertaken to identify effective substitutes for part of the Cr in 304 stainless steel as a method of conserving the strategic element Cr. Although special emphasis was placed on tensile properties, oxidation and corrosion resistance were also examined. Results indicate that over the temperature range of -196 C to 540 C the yield stress of experimental austenitic alloys with only 12 percent Cr compare favorably with the 18 percent Cr in 304 stainless steel. Oxidation resistance and in most cases corrosion resistance for the experimental alloys were comparable to the commercial alloy. Effective substitutes for Cr included Al, Mo, Si, Ti, and V, while Ni and Mn contents were increased to maintain an austenitic structure.

  2. Effect of Al on the mechanical properties and corrosion resistance of Pb-Al alloy

    Science.gov (United States)

    LU, Zhicheng; LIU, Zhenlin; LI, Yongliang; WU, Dan; WANG, Fuming

    2017-05-01

    A set of binary Pb-Al alloys with different Al contents were designed in this work. The mechanical properties and corrosion resistance of Pb-Al alloys were investigated with help of tensile test, Charpy V-notch impact test and salt spray corrosion test (SSCT). And the microstructure was observed by optical microscopy. The results showed that microstructure of all alloys were twin structure, and the twin structure was gradually refined with the increase of Al content. Al dissolved in matrix could significantly improve the tensile strength, impact energy and corrosion resistance. However, a higher content of Al would harm the mechanical properties and corrosion resistance. It may be due to the heterogeneous precipitation of Al rich phase.

  3. Stress corrosion cracking resistance of aluminum alloy 7000 series after two-step aging

    Directory of Open Access Journals (Sweden)

    Jegdić Bore V.

    2015-01-01

    Full Text Available The effect of one step-and a new (short two-step aging on the resistance to stress corrosion cracking of an aluminum alloy 7000 series was investigated, using slow strain rate test and fracture mechanics method. Aging level in the tested alloy was evaluated by means of scanning electron microscopy and measurements of electrical resistivity. It was shown that the alloy after the new two-step aging is significantly more resistant to stress corrosion cracking. Values of tensile properties and fracture toughness are similar for both thermal states. Processes that take place at the crack tip have been considered. The effect of the testing solution temperature on the crack growth rate on the plateau was determined. Two values of the apparent activation energy were obtained. These values correspond to different processes that control crack growth rate on the plateau at higher and lower temperatures. [Projekat Ministarstva nauke Republike Srbije, br. TR 34028 i br. TR 34016

  4. Plasma enhanced chemical vapor deposition of metalboride interfacial layers as diffusion barriers for nanostructured diamond growth on cobalt containing alloys CoCrMo and WC-Co

    Science.gov (United States)

    Johnston, Jamin M.

    This work is a compilation of theory, finite element modeling and experimental research related to the use of microwave plasma enhanced chemical vapor deposition (MPECVD) of diborane to create metal-boride surface coatings on CoCrMo and WC-Co, including the subsequent growth of nanostructured diamond (NSD). Motivation for this research stems from the need for wear resistant coatings on industrial materials, which require improved wear resistance and product lifetime to remain competitive and satisfy growing demand. Nanostructured diamond coatings are a promising solution to material wear but cannot be directly applied to cobalt containing substrates due to graphite nucleation. Unfortunately, conventional pre-treatment methods, such as acid etching, render the substrate too brittle. Thus, the use of boron in a MPECVD process is explored to create robust interlayers which inhibit carbon-cobalt interaction. Furthermore, modeling of the MPECVD process, through the COMSOL MultiphysicsRTM platform, is performed to provide insight into plasma-surface interactions using the simulation of a real-world apparatus. Experimental investigation of MPECVD boriding and NSD deposition was conducted at surface temperatures from 700 to 1100 °C. Several well-adhered metal-boride surface layers were formed: consisting of CoB, CrB, WCoB, CoB and/or W2CoB2. Many of the interlayers were shown to be effective diffusion barriers against elemental cobalt for improving nucleation and adhesion of NSD coatings; diamond on W2CoB2 was well adhered. However, predominantly WCoB and CoB phase interlayers suffered from diamond film delamination. Metal-boride and NSD surfaces were evaluated using glancing-angle x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), cross-sectional scanning electron microscopy (SEM), energy dispersive x-ray spectroscopy (EDS), micro-Raman spectroscopy, nanoindentation, scratch testing and epoxy pull testing. COMSOL MultiphysicsRTM was used to construct a

  5. Increased corrosion resistance of the AZ80 magnesium alloy by rapid solidification.

    Science.gov (United States)

    Aghion, E; Jan, L; Meshi, L; Goldman, J

    2015-11-01

    Magnesium (Mg) and Mg-alloys are being considered as implantable biometals. Despite their excellent biocompatibility and good mechanical properties, their rapid corrosion is a major impediment precluding their widespread acceptance as implantable biomaterials. Here, we investigate the potential for rapid solidification to increase the corrosion resistance of Mg alloys. To this end, the effect of rapid solidification on the environmental and stress corrosion behavior of the AZ80 Mg alloy vs. its conventionally cast counterpart was evaluated in simulated physiological electrolytes. The microstructural characteristics were examined by optical microscopy, SEM, TEM, and X-ray diffraction analysis. The corrosion behavior was evaluated by immersion, salt spraying, and potentiodynamic polarization. Stress corrosion resistance was assessed by Slow Strain Rate Testing. The results indicate that the corrosion resistance of rapidly solidified ribbons is significantly improved relative to the conventional cast alloy due to the increased Al content dissolved in the α-Mg matrix and the correspondingly reduced presence of the β-phase (Mg17 Al12 ). Unfortunately, extrusion consolidated solidified ribbons exhibited a substantial reduction in the environmental performance and stress corrosion resistance. This was mainly attributed to the detrimental effect of the extrusion process, which enriched the iron impurities and increased the internal stresses by imposing a higher dislocation density. In terms of immersion tests, the average corrosion rate of the rapidly solidified ribbons was alloy and 26 mm/year for the rapidly solidified extruded ribbons. © 2014 Wiley Periodicals, Inc.

  6. Investigation of processing effects on the corrosion resistance of Ti20Mo alloy in saline solutions

    International Nuclear Information System (INIS)

    Bolat, G.; Izquierdo, J.; Gloriant, T.; Chelariu, R.; Mareci, D.; Souto, R.M.

    2015-01-01

    Graphical abstract: - Highlights: • Alloy fabrication method affects both surface finish and corrosion resistance. • More porous surface finish and higher wettability produced by powder sintering. • Passive layer formed on sintered alloy breaks down in saline solution. • Increase in surface porosity facilitated electron transfer through the oxide film. • More corrosion resistant alloy produced by cold crucible levitation melting. - Abstract: The electrochemical properties of Ti20Mo alloys prepared using different fabrication procedures, namely cold crucible levitation melting (CCLM) and powder sintering, were investigated using linear potentiodynamic polarization and EIS measurements. The surface condition was established using AFM, with the observation of a more porous surface finish in the case of powder sintering. A major effect of surface conditioning on the corrosion resistance of Ti20Mo alloys was observed, where the compact finish exhibits a superior corrosion resistance in chloride-containing saline solutions. Less insulating surfaces towards electron exchange resulted for the more porous finish as revealed by scanning electrochemical microscopy (SECM)

  7. Sulfuration resistance of five experimental Ag-Pd-Au-Cu alloys with low Pd content of 10 or 12%.

    Science.gov (United States)

    Saitoh, Setsuo; Araki, Yoshima; Taira, Masayuki

    2006-06-01

    Commercial Ag-based alloy (46Ag-20Pd-12Au-20Cu alloy) is widely used in Japan as a casting alloy. As opposed to the commercial composition, we prepared five experimental Ag-based alloys with reduced Pd content of 10 or 12%, increased Au content of 20 to 30%, and reduced Cu content of 12 to 20%. We then evaluated their sulfuration resistance by analyzing cast specimen surfaces dipped in 0.1% Na2S solution with SEM/EPMA, TF-XRD, and XPS. It became evident that all alloys were susceptible to sulfuration in the segregated Ag-rich Pd-poor phases. The degree and speed of sulfuration, however, differed among the six alloys examined. In particular, one experimental alloy (46Ag-10Pd-30Au-12Cu) possessed a sulfuration resistance equal or superior to that of commercial Ag-based alloy, while the other four experimental alloys were inferior in sulfuration resistance. Based on the results of this study, we concluded that our newly developed 46Ag-10Pd-30Au-12Cu alloy could be employed as a new sulfuration-resistant Ag-based casting alloy--which is especially useful if the price of Pd is skyrocketing again.

  8. In vitro evaluation of the bonding of auto-polymerizing soft denture liner to cobalt-chromium alloy.

    Science.gov (United States)

    Minami, H; Suzuki, S; Ohashi, H; Minesaki, Y; Tanaka, T

    2005-06-01

    This study evaluated the effects of surface pre-treatments on the bonding of auto-polymerizing silicone soft denture liner to a Co-Cr alloy denture base after cyclic thermal stressing. The bonding surfaces of Co-Cr alloy cylinders (8 mm diameter and 4 mm high) were polished with a 600-grit silicon carbide paper. The bonding surfaces received one of three pre-treatments, which included either the application of a metal primer, a metal primer after air abrasion, or a resin primer after adhesive resin coating. Tensile specimens were fabricated by polymerizing a 2-mm thickness of soft denture liner between a pair of pre-treated denture base cylinders. Failure loads were measured by tensile testing after subjecting the specimen to 0, 5, 10, 20, and 30 thousand thermal cycles. Seven specimens were fabricated for 15 groups, including three pre-treatments and five thermal cycle groups. Failure loads of resin-bonded specimens, which were formerly reported, were used as references. All data were statistically analysed by two-way anova and Bonferroni test at the 95% confidence level. Adhesive resin coating of the metal surface was effective in enhancing the failure loads up to 5000 thermal cycles. However, failure loads of all metal-bonded groups were significantly lower than those of resin-bonded groups at all thermal cycling intervals. The results of this in vitro study implied that polymerizing adhesive resin on the Co-Cr alloy might be a promising method, when the clinicians need to acquire improved bonding of an auto-polymerizing soft denture liner to Co-Cr alloy denture bases.

  9. Corrosion behavior of nickel-containing alloys in artificial sweat.

    Science.gov (United States)

    Randin, J P

    1988-07-01

    The corrosion resistance of various nickel-containing alloys was measured in artificial sweat (perspiration) using the Tafel extrapolation method. It was found that Ni, CuNi 25 (coin alloy), NiAl (colored intermetallic compounds), WC + Ni (hard metal), white gold (jewelry alloy), FN42 and Nilo Alby K (controlled expansion alloys), and NiP (electroless nickel coating) are in an active state and dissolve readily in oxygenated artificial sweat. By contrast, austenitic stainless steels, TiC + Mo2C + Ni (hard metal), NiTi (shape-memory alloy), Hastelloy X (superalloy), Phydur (precipitation hardening alloy), PdNi and SnNi (nickel-containing coatings) are in a passive state but may pit under certain conditions. Cobalt, Cr, Ti, and some of their alloys were also investigated for the purpose of comparison. Cobalt and its alloys have poor corrosion resistance except for Stellite 20. Chromium and high-chromium ferritic stainless steels have a high pitting potential but the latter are susceptible to crevice corrosion. Ti has a pitting potential greater than 3 V. Comparison between the in vitro measurements of the corrosion rate of nickel-based alloys and the clinical observation of the occurrence of contact dermatitis is discussed.

  10. Corrosion behavior of dental alloys in various types of electrolyzed water.

    Science.gov (United States)

    Dong, Hongwei; Nagamatsu, Yuki; Chen, Ker-Kong; Tajima, Kiyoshi; Kakigawa, Hiroshi; Shi, Sizhen; Kozono, Yoshio

    2003-12-01

    The corrosion behavior of dental alloys was examined in electrolyzed strong acid water, weak acid water and neutral water using a 7-day immersion test. The precious metal alloys, gold alloy. Au-Ag-Pd alloy and silver alloy showed the greatest surface color change and dissolution of constituents in the strong acid water and the smallest in the neutral water. The release of Au from gold alloy was especially marked in the strong acid water. Co-Cr alloy showed greater corrosion and tarnish resistance in the strong acid water rather than in the weak acid water and the neutral water. X-ray microanalysis revealed that the corrosion products on the precious metal alloys were silver chloride crystals and the thin brown products on Co-Cr alloy were cobalt and chromium oxides. Ti was sound in all three types of electrolyzed water. The neutral water appeared the least corrosive to metals among the three types showing equivalent bactericidal activity.

  11. A spot test for detection of cobalt release – early experience and findings

    DEFF Research Database (Denmark)

    Thyssen, Jacob P.; Menné, Torkil; Johansen, Jeanne D.

    2010-01-01

    Background: It is often difficult to establish clinical relevance of metal exposure in cobalt-allergic patients. Dermatologists and patients may incorrectly assume that many metallic items release cobalt at levels that may cause cobalt dermatitis. Cobalt-allergic patients may be unaware...... also be used as a gel test if combined with an agar preparation. We found no false-positive reactions when testing metals and alloys known not to contain cobalt. However, one cobalt-containing alloy, which elicited cobalt dermatitis in cobalt-allergic patients, was negative upon cobalt gel testing....... Conclusions: The cobalt test detects amounts of cobalt release that approximate the elicitation concentration seen in cobalt-allergic patients. It may serve as a useful tool in dermatology offices and workplaces....

  12. Amorphous Metallic Alloys: Pathways for Enhanced Wear and Corrosion Resistance

    Science.gov (United States)

    Aditya, Ayyagari; Felix Wu, H.; Arora, Harpreet; Mukherjee, Sundeep

    2017-11-01

    Amorphous metallic alloys are widely used in bulk form and as coatings for their desirable corrosion and wear behavior. Nevertheless, the effects of heat treatment and thermal cycling on these surface properties are not well understood. In this study, the corrosion and wear behavior of two Zr-based bulk metallic glasses were evaluated in as-cast and thermally relaxed states. Significant improvement in wear rate, friction coefficient, and corrosion penetration rate was seen for both alloys after thermal relaxation. A fully amorphous structure was retained with thermal relaxation below the glass transition. There was an increase in surface hardness and elastic modulus for both alloys after relaxation. The improvement in surface properties was explained based on annihilation of free volume.

  13. Polarization and resistivity measurements of post-crystallization changes in amorphous Fe-B-Si alloys

    International Nuclear Information System (INIS)

    Chattoraj, I.; Bhattamishra, A.K.; Mitra, A.

    1993-01-01

    The effects of grain growth and compositional changes on the electrochemical behavior and the resistivity of amorphous iron-boron-silicon (Fe 77.5 B 15 Si 7.5 ) alloys after crystallization were studied. Deterioration of the protective passive film was observed, along with increased annealing. Potentiodynamic polarization provided excellent information about microstructural and chemical changes. It was concluded that electrochemical measurements could be used in conjunction with resistivity measurements in direct studies of grain growth and chemical changes occurring in different phases of the devitrified alloy

  14. Compatibility of heat resistant alloys with boron carbide, 5

    International Nuclear Information System (INIS)

    Baba, Shinichi; Kurasawa, Toshimasa; Endow, Taichi; Someya, Hiroyuki; Tanaka, Isao.

    1986-08-01

    This paper includes an experimental result of out-of-pile compatibility and capsule design for irradiation test in Japan Materials Testing Reactor (JMTR). The compatibility between sheath material and neutron absorber materials for control rod devices (CRD) was examined for potential use in a very high temperature reactor (VHTR) which is under development at JAERI. The purpose of the compatibility tests are preliminary evaluation of safety prior to irradiation tests. Preliminary compatibility evaluation was concerned with three items as follows : 1) Lithium effects on the penetrating reaction of Incoloy 800H alloy in contact with a mixture of boronated graphite and lithium hydroxide powders, 2) Short term tensile properties of Incoloy 800H and Hastelloy XR alloy reacted with boronated graphite and fracture mode analysis, 3) Reaction behavior of both alloys under transient power conditions of a VHTR. It was clear that the reaction rate constant of the Incoloy 800H alloy was accelerated by doping lithium hydroxide into the boron carbide and graphite powder. The mechanical properties of Incoloy 800H and Hastelloy XR alloy reacted with boronated graphite were decreased. Ultimate tensile strength and tensile ductilities at temperatures over 850 deg C were reduced, but there was no change in the proof (yield) stress. Both alloys exhibited a brittle intergranular fracture mode during transient power conditions of a VHTR and also exhibited severe penetration. Irradiation capsules for compatibility test were designed to simulate three irradiation conditions of VHTR: 1) steady state for VHTR, 2) Transient power condition, 3) Service limited life of CRD. Capsule irradiation experiments have been carried out satisfactorily and thus confirm the validity of the capsule design procedure. (author)

  15. Adhesion of dental porcelain to cast, milled, and laser-sintered cobalt-chromium alloys: shear bond strength and sensitivity to thermocycling.

    Science.gov (United States)

    Serra-Prat, Josep; Cano-Batalla, Jordi; Cabratosa-Termes, Josep; Figueras-Àlvarez, Oscar

    2014-09-01

    New technologies have led to the introduction of new materials, so an evaluation of the adhesion of ceramics to these materials is needed. The purpose of this study was to compare the shear bond strength of dental porcelain to cast, milled, and laser-sintered cobalt-chromium alloys, and to investigate the adhesive bond and failure type after thermocycling, 90 metal cylinders (10 mm diameter and 10 mm height) were prepared from cast (30 specimens), milled (30 specimens), and laser-sintered (30 specimens) alloys. Ceramic cylinders (2.5 mm diameter and 4 mm length) were fused to the alloy cylinders. For each group, 15 specimens were thermocycled 5500 times at temperatures between 4°C and 60°C before testing. After testing, the specimen surfaces were visually examined to determine the failure mode. Differences in adhesion values according to manufacturing method, testing condition (thermocycling or no thermocycling), and interaction between the factors were evaluated with a 2-way ANOVA. The χ(2) test (95% confidence level) was performed to determine whether the failure mode was associated with the testing condition. Adhesion strengths for the nonthermocycled specimens were 42.79 ±14.14 MPa (cast), 37.56 ±9.18 MPa (milled), and 29.09 ±6.95 MPa (laser-sintered), and, for the thermocycled specimens, 16.52 ±8.96 MPa (cast), 22.21 ±13.25 MPa (milled), and 24.28 ±10.13 MPa (laser-sintered). Two-way ANOVA results indicated no statistically significant differences in adhesion among the manufacturing methods (P=.257), but statistically significant differences were observed according to both testing conditions (Papplications. No significant adhesion differences were observed between cast, milled, and laser-sintered specimens, or among thermocycled and nonthermocycled laser-sintered specimens. However, significant adhesion differences were observed among the thermocycled and nonthermocycled cast and the milled specimens. Copyright © 2014 Editorial Council for the

  16. Straining electrode behavior and corrosion resistance of nickel base alloys in high temperature acidic solution

    International Nuclear Information System (INIS)

    Yamanaka, Kazuo

    1992-01-01

    Repassivation behavior and IGA resistance of nickel base alloys containing 0∼30 wt% chromium was investigated in high temperature acid sulfate solution. (1) The repassivation rate was increased with increasing chromium content. And so the amounts of charge caused by the metal dissolution were decreased with increasing chromium content. (2) Mill-annealed Alloy 600 suffered IGA at low pH environment below about 3.5 at the fixed potentials above the corrosion potential in 10%Na 2 SO 4 +H 2 SO 4 solution at 598K. On the other hand, thermally-treated Alloy 690 was hard to occur IGA at low pH environments which mill-annealed Alloy 600 occurred IGA. (3) It was considered that the reason, why nickel base alloys containing high chromium content such as Alloy 690 (60%Ni-30%Cr-10%Fe) had high IGA/SCC resistance in high temperature acidic solution containing sulfate ion, is due to both the promotion of the repassivation and the suppression of the film dissolution by the formation of the dense chromium oxide film

  17. Synthesis and characterization of mixtures of cobalt and titanium oxides by mechanical alloyed and Sol-Gel;Sintesis y caracterizacion de mezclas de oxidos de cobalto y titanio por aleado mecanico y Sol-Gel

    Energy Technology Data Exchange (ETDEWEB)

    Basurto S, R.; Bonifacio M, J.; Fernandez V, S. M., E-mail: rafael.basurto@inin.gob.m [ININ, Departamento de Quimica, Carretera Mexico-Toluca s/n, Ocoyoacac 52750, Estado de Mexico (Mexico)

    2009-07-01

    The mechanical alloyed techniques continued by combustion and Sol-Gel method, were used for the synthesis of CoTiO{sub 3}. With the first technique was used Co{sub 3}O{sub 4} obtained in a balls mill SPEX in argon atmosphere, using cobalt nitrate and urea, the combustion is realized at 400 and 500 C, the characterization by X-ray diffraction showed the obtaining of the valence oxide mixed of cobalt with crystallite size from 10 to 12.5 nm and the particle size of 60 to 75 nm was obtained by scanning electron microscopy. To prepare the CoTiO{sub 3}, the obtained Co{sub 3}O{sub 4} was mixed with TiO{sub 2} on a relationship in weight (1:1) and with a milling time of 2.5 h and the combustion at 800 C. the mixed oxide of titanium cobalt was also obtained by the Sol-Gel technique starting from cobalt chloride and titanium propoxide in acetic-water acid, the gel is burned to temperature of 300, 500, 700 and 900 C, finding that this last temperature it is that provides the compound with crystalline size from 50 to 75 nm. (Author)

  18. The effect of Electro Discharge Machining (EDM) on the corrosion resistance of dental alloys.

    Science.gov (United States)

    Ntasi, Argyro; Mueller, Wolf Dieter; Eliades, George; Zinelis, Spiros

    2010-12-01

    The aim of the present study was to evaluate the effect of Electro Discharge Machining (EDM) on the corrosion resistance of two types of dental alloys used for fabrication of implant retained superstructures. Two groups of specimens were prepared from a Co-Cr (Okta-C) and a grade II cpTi (Biotan) alloys respectively. Half of the specimens were subjected to EDM with Cu electrodes and the rest were conventionally finished (CF). The corrosion resistance of the alloys was evaluated by anodic polarization in Ringer's solution. Morphological and elemental alterations before and after corrosion testing were studied by SEM/EDX. Six regions were analyzed on each surface before and after corrosion testing and the results were statistically analyzed by paired t-test (a=0.05). EDM demonstrated inferior corrosion resistance compared to CF surfaces, the latter being passive in a wider range of potential demonstrating higher polarization resistance and lower I(corr) values. Morphological alterations were found before and after corrosion testing for both materials tested after SEM analysis. EDX showed a significant decrease in Mo, Cr, Co, Cu (Co-Cr) and Ti, Cu (cpTi) after electrochemical testing plus an increase in C. According to the results of this study the EDM procedure decreases the corrosion resistance of both the alloys tested, increasing thus the risk of possible adverse biological reactions. Copyright © 2010 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

  19. New metallurgical feasibilities in improvement of steel and alloy corrosion resistance

    International Nuclear Information System (INIS)

    Khasin, G.A.; Pokrovskij, A.B.; Krylov, S.M.; Leonovich, B.I.; Tomilov, V.I.

    1981-01-01

    New methods of the improvement of steel and alloy corrosion resistance are described. Some versions of technology of especially corrosion resistant steels melting in arc furnace with low carbon content are developed. One of such methods provides the complete decarburization of iron-nickel melt by oxygen-air mixture, the transition to the reduction period without the skimming of oxidation slag, ferrochromium melting at the expense of excess heat and the final reduction and refining of metal by inert gas blowing in the ladle. The 03Kh18N11, 03Kh18N12, 03Kh21N21M4GB, 03Kh17N14M3 and other steels are melted using this technology. Lately the melting technology of corrosion resistant and other alloyed steels and alloys with program thermo-time treatment of melts in arc and open induction furnaces is introduced. The method of phase equilibria calculation, which permits to estimate qualitatively and quantitatively the phases, formed in liquid metal during its solidification, and in solid metal, depending on temperature and composition of metal, is developed. Using the casting method, the production of corrosion resistant compositions with titanium carbides, is realized. Heat treatment and deformation methods of corrosion resistant steels and alloys are also discussed [ru

  20. Resistance of WE43 and ZRE1 Magnesium Alloys to Gas Corrosion

    Directory of Open Access Journals (Sweden)

    Przeliorz R.

    2017-06-01

    Full Text Available In spite of the fact that in most applications, magnesium alloys are intended for operation in environments with room temperature, these alloys are subject to elevated temperature and oxidizing atmosphere in various stages of preparation (casting, welding, thermal treatment. At present, the studies focus on development of alloys with magnesium matrix, intended for plastic forming. The paper presents results of studies on oxidation rate of WE43 and ZRE1 magnesium foundry alloys in dry and humidified atmosphere of N2+1%O2. Measurements of the oxidation rate were carried out using a Setaram thermobalance in the temperature range of 350-480°C. Corrosion products were analyzed by SEM-SEI, BSE and EDS. It was found that the oxide layer on the WE43 alloy has a very good resistance to oxidation. The high protective properties of the layer should be attributed to the presence of yttrium in this alloy. On the other hand, a porous, two-layer scale with a low adhesion to the substrate forms on the ZRE1 alloy. The increase in the sample mass in dry gas is lower than that in humidified gas.

  1. Corrosion resistant coatings for uranium and uranium alloys

    International Nuclear Information System (INIS)

    Weirick, L.J.; Lynch, C.T.

    1977-01-01

    Coatings to prevent the corrosion of uranium and uranium alloys are considered in two military applications: kinetic energy penetrators and aircraft counterweights. This study, which evaluated organic films and metallic coatings, demonstrated that the two most promising coatings are based on an electrodeposited nickel system and a galvanized zinc system

  2. HOW TO MAKE MAGNESIUM ALLOYS BE RESISTANT TO OPERATIONAL RISKS

    Directory of Open Access Journals (Sweden)

    N. M. Chigrinova

    2016-01-01

    Full Text Available The paper studies regularities and mechanisms of structure and phase formation in the surface layers of magnesium alloys when they are processed by method of micro-arc oxidation [MAO]. It has been determined that the same specific features of structure formation, namely: existence of a thin dense inner sublayer and a thicker outer sublayer with developed porosity are common for all types of coatings on the surface of magnesium and aluminum alloys. Such structural state of a protective coating can not be considered as a guaranteed protection against operational impacts, taking into account the fields of their primary application that is aviation construction, automotive construction, instrumentation, building construction, etc. The paper has analyzed the effect of alkaline electrolytes with varying chemical composition due to additions of sodium fluoride or potassium on the structure and properties of these alloys as well as on the level of basic performance characteristics of the layers formed in such electrolytes. On the basis of the analysis a conclusion has been made that it is possible to extend their life-span under operational conditions. It has been revealed that the existing techniques and methods for process control of MAO aluminum and magnesium alloys, particularly processing modes and technological equipment capacity determine a nature of structure formation and changes in a phase composition of the formed coatings.

  3. Isothermal and cyclic oxidation resistance of pack siliconized Mo–Si–B alloy

    Energy Technology Data Exchange (ETDEWEB)

    Majumdar, Sanjib, E-mail: sanjib@barc.gov.in

    2017-08-31

    Highlights: • Pack-siliconizing of Mo–Si–B alloy improves its oxidation resistance at 750, 900 and 1400 °C. • A marginal weight change of the coated alloy is detected in isothermal and cyclic oxidation tests. • Kinetics of growth of protective SiO{sub 2} scale is much faster at 1400 °C. • Self-healing SiO{sub 2} is developed at the cracks formed in MoSi{sub 2} layer during cyclic oxidation tests. - Abstract: Oxidation behaviour of MoSi{sub 2} coated Mo–9Si–8B–0.75Y (at.%) alloy has been investigated at three critical temperatures including 750, 900 and 1400 °C in static air. Thermogravimetric analysis (TGA) data indicates a remarkable improvement in the oxidation resistance of the silicide coated alloy in both isothermal and cyclic oxidation tests. The cross-sectional scanning electron microscopy and energy dispersive spectroscopic analysis reveal the occurrence of internal oxidation particularly at the crack fronts formed in the outer MoSi{sub 2} layer during thermal cycling. The dominant oxidation mechanisms at 750–900 °C and 1400 °C are identified. Development of MoB inner layer further improves the oxidation resistance of the silicide coated alloy.

  4. Investigations into the corrosion resistance of copper aluminium alloys. Effect of phosphorus as corrosion resistant third alloying element in the ternary system CuAl20P1

    International Nuclear Information System (INIS)

    Allwardt, A.

    1997-01-01

    The effect of phosphorus on the corrosion resistance of Al-bronzes is studied in detail in this work. A literature review showed that there are a lot of things known about the microstructure and the mechanical properties of Al-bronzes. In spite of their corrosion resistance the corrosion properties and the structure of the protective oxide films of Al-bronzes were seldom a matter of interest. Systematic studies of the influence of different alloying elements on the oxide film and the corrosion properties are rare. Therefore, it is not possible to predict the corrosion resistance of Al-bronzes, made by alloying particular elements. The high corrosion resistance of the new alloy CuAl 20 P 1 was the reason to investigate the influence of phosphorus on the corrosion properties of Al-bronzes in more detail. A systematic study of the microstructure and the corrosion properties of Cu, CuP x , CuAl 20 and CuAl 20 P x offers an insight into the effect of aluminium and phosphorus on the formation of the oxide film on Al-bronzes. It was found that there exists a critical amount of 1 at.-% of phosphorus. Above and below this amount the corrosion resistance becomes worse. This behaviour could be explained by XPS-and electrochemical measurements. Although there are still some questions about the influence of phosphorus on the corrosion resistance of Al-bronzes, this work has produced some important results, which in the future may be helpful to develop new high corrosion resistant Al-bronzes more efficiently: - on clean surface Al-bronze, the oxidation of Al and Cu takes place simultaneously, - Al promotes the formation of Cu 2 O but impedes the formation of Cu(II)-oxide/-hydride in neutral solutions, - P impedes the formation of Cu 2 O and as a consequence promotes the formation of aluminium oxide. This results in a higher amount of Al in the oxide film on the surface of the alloy, which leads to a better corrosion resistance. (author) figs., tabs., 106 refs

  5. Electrocatalysts with platinum, cobalt and nickel preparations by mechanical alloyed and CVD for the reaction of oxygen reduction

    International Nuclear Information System (INIS)

    Garcia C, M. A.

    2008-01-01

    In this research, the molecular oxygen reduction reaction (ORR) was investigated on electrocatalysts of Co, Ni, Pt and their alloys CoNi, PtCo, PtNi and PtCoNi by using H 2 SO 4 0.5 and KOH 0.5 M solutions as electrolytes. The electrocatalysts were synthesized by Mechanical Alloying (MA) and Chemical Vapor Deposition (CVD) processes. For MA, metallic powders were processed during 20 h of milling in a high energy SPEX 8000 mill. For CVD, a hot-wall reactor was utilized and Co, Ni and Pt acetilactetonates were used as precursors. Films were deposited at a total pressure of 1 torr and temperatures of 400-450 C. Electrocatalysts were characterized by X-Ray Diffraction (XRD). Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and Energy Dispersive X-Ray Spectroscopy (EDS). Electrocatalysts prepared by mechanical alloying showed a homogeneously dispersed agglomeration of particles with nano metric size. Electrocatalysts obtained by CVD showed, in some cases, non uniform films, with particles of nano metric size, as well. The electrocatalytic performance was evaluated by using the Rotating Disk Electrode technique (RDE). Electrocatalysts prepared by MA showed higher activity than those obtained by CVD. All electrocatalysts were evaluated in alkaline media. Only electrocatalysts containing Pt were evaluated in acid media, because those materials with Co, Ni and their alloys showed instability in acidic media. Most electrocatalysts followed a mechanism for the ORR producing a certain proportion of H 2 O 2 . All electrocatalysts, exhibited a fair or good electrocatalytic activity in comparison with other similar reported materials. It was found that MA and CVD are appropriate processes to prepare electrocatalysts for the ORR with particles of nano metric size and performing with an acceptable catalytic activity. PtCoNi 70-23-7% by MA and PtCoNi-CVD electrocatalysts showed the highest activity in alkaline media, while in acidic electrolyte PtCoNi 70

  6. Influence of Crucible Materials on High-temperature Properties of Vacuum-melted Nickel-chromium-cobalt Alloy

    Science.gov (United States)

    Decker, R F; Rowe, John P; Freeman, J W

    1957-01-01

    A study of the effect of induction-vacuum-melting procedure on the high-temperature properties of a titanium-and-aluminum-hardened nickel-base alloy revealed that a major variable was the type of ceramic used as a crucible. Reactions between the melt and magnesia or zirconia crucibles apparently increased high-temperature properties by introducing small amounts of boron or zirconium into the melts. Heats melted in alumina crucibles had relatively low rupture life and ductility at 1,600 F and cracked during hot-working as a result of deriving no boron or zirconium from the crucible.

  7. Nickel acts as an adjuvant during cobalt sensitization

    DEFF Research Database (Denmark)

    Bonefeld, Charlotte Menne; Nielsen, Morten Milek; Vennegaard, Marie T.

    2015-01-01

    Metal allergy is the most frequent form of contact allergy with nickel and cobalt being the main culprits. Typically, exposure comes from metal-alloys where nickel and cobalt co-exist. Importantly, very little is known about how co-exposure to nickel and cobalt affects the immune system. We...... investigated these effects by using a recently developed mouse model. Mice were epicutaneously sensitized with i) nickel alone, ii) nickel in the presence of cobalt, iii) cobalt alone, or iv) cobalt in the presence of nickel, and then followed by challenge with either nickel or cobalt alone. We found...... that sensitization with nickel alone induced more local inflammation than cobalt alone as measured by increased ear-swelling. Furthermore, the presence of nickel during sensitization to cobalt led to a stronger challenge response to cobalt as seen by increased ear-swelling and increased B and T cell responses...

  8. Thermal Stability of Platinum-Cobalt Bimetallic Nanoparticles: Chemically Disordered Alloys, Ordered Intermetallics, and Core-Shell Structures.

    Science.gov (United States)

    Huang, Rao; Shao, Gui-Fang; Zhang, Yang; Wen, Yu-Hua

    2017-04-12

    Pt-Co bimetallic nanoparticles are promising candidates for Pt-based nanocatalysts and magnetic-storage materials. By using molecular dynamics simulations, we here present a detailed examination on the thermal stabilities of Pt-Co bimetallic nanoparticles with three configurations including chemically disordered alloy, ordered intermetallics, and core-shell structures. It has been revealed that ordered intermetallic nanoparticles possess better structural and thermal stability than disordered alloyed ones for both Pt 3 Co and PtCo systems, and Pt 3 Co-Pt core-shell nanoparticles exhibit the highest melting points and the best thermal stability among Pt-Co bimetallic nanoparticles, although their meltings all initiate at the surface and evolve inward with increasing temperatures. In contrast, Co-Pt core-shell nanoparticles display the worst thermal stability compared with the aforementioned nanoparticles. Furthermore, their melting initiates in the core and extends outward surface, showing a typical two-stage melting mode. The solid-solid phase transition is discovered in Co core before its melting. This work demonstrates the importance of composition distribution to tuning the properties of binary nanoparticles.

  9. Influence of Chromium-Cobalt-Molybdenum Alloy (ASTM F75 on Bone Ingrowth in an Experimental Animal Model

    Directory of Open Access Journals (Sweden)

    Jésica Zuchuat

    2017-12-01

    Full Text Available Cr-Co-Mo (ASTM F75 alloy has been used in the medical environment, but its use as a rigid barrier membrane for supporting bone augmentation therapies has not been extensively investigated. In the present study, Cr-Co-Mo membranes of different heights were placed in New Zealand white, male rabbit tibiae to assess the quality and volume of new bone formation, without the use of additional factors. Animals were euthanized at 20, 30, 40, and 60 days. Bone formation was observed in all of the cases, although the tibiae implanted with the standard membranes reached an augmentation of bone volume that agreed with the density values over the timecourse. In all cases, plasmatic exudate was found under the membrane and in contact with the new bone. Histological analysis indicated the presence of a large number of chondroblasts adjacent to the inner membrane surface in the first stages, and osteoblasts and osteocytes were observed under them. The bone formation was appositional. The Cr-Co-Mo alloy provides a scaffold with an adequate microenvironment for vertical bone volume augmentation, and the physical dimensions and disposition of the membrane itself influence the new bone formation.

  10. Isothermal and cyclic oxidation resistance of pack siliconized Mo-Si-B alloy

    Science.gov (United States)

    Majumdar, Sanjib

    2017-08-01

    Oxidation behaviour of MoSi2 coated Mo-9Si-8B-0.75Y (at.%) alloy has been investigated at three critical temperatures including 750, 900 and 1400 °C in static air. Thermogravimetric analysis (TGA) data indicates a remarkable improvement in the oxidation resistance of the silicide coated alloy in both isothermal and cyclic oxidation tests. The cross-sectional scanning electron microscopy and energy dispersive spectroscopic analysis reveal the occurrence of internal oxidation particularly at the crack fronts formed in the outer MoSi2 layer during thermal cycling. The dominant oxidation mechanisms at 750-900 °C and 1400 °C are identified. Development of MoB inner layer further improves the oxidation resistance of the silicide coated alloy.

  11. Weld-brazing - a new joining process. [combination resistance spot welding and brazing of titanium alloys

    Science.gov (United States)

    Bales, T. T.; Royster, D. M.; Arnold, W. E., Jr.

    1972-01-01

    A joining process designated weld brazing which combines resistance spot welding and brazing has been developed. Resistance spot welding is used to position and align the parts as well as to establish a suitable faying surface gap for brazing. Fabrication is then completed by capillary flow of the braze alloy into the joint. The process has been used successfully to fabricate Ti-6Al-4V titanium alloy joints using 3003 aluminum braze alloy. Test results obtained on single overlap and hat-stiffened structural specimens show that weld brazed joints are superior in tensile shear, stress rupture, fatigue, and buckling than joint fabricated by spotwelding or brazing. Another attractive feature of the process is that the brazed joints is hermetically sealed by the braze material.

  12. The feed forward neural network model for liquid-liquid extraction and separation of cobalt (II) from sodium acetate media using cyanex 272

    Science.gov (United States)

    Sudibyo, Aji, B. B.; Priyanto, S.

    2017-03-01

    Cobalt is one of the precious ferromagnetic metals, which widely used in the preparation of magnetic, wear-resistant and high-strength alloys. This metal was not found naturally in single metal form but is found as impurities in nickel or copper ore. The extraction process is one of the methods to separate cobalt from its impurities. However, this process needs an expensive organic solution. In practice, changing the composition of chemicals composition in extraction process always affect at a high cost. Therefore, the development of the artificial neural network (ANN) model to model the cobalt extraction process can serve as an important tool for predicting and investigating the optimum production for the cobalt extraction without the need to run the actual experiment. Hence, the development of the ANN model of cobalt extraction model is essential to simulate the process, which can lead to high yields of cobalt production. In this work a selected optimum multiple-input-single-output (MISO) model of feed forward neural network (FFNN) was used to predict the percentage of cobalt extraction. MISO FFNN with 20, 30 and 50 hidden nodes were used to simulate cobalt extraction process. The simulation results achieved was compared with data available in the literature. The results show that MISO FFNN with 50 hidden nodes has the best performance. The optimum result of MISO FFNN then exported to Simulink model in Matlab environment, hence make it easy to use in predicting and investigating for the optimum production of the cobalt extraction.

  13. Correlation of electrical resistivity with microstructure in an Fe-Co-2% V alloy

    International Nuclear Information System (INIS)

    Ashby, J.A.; Flower, H.M.; Rawlings, R.D.

    1978-01-01

    The resistivity of an Fe-Co-2% V alloy in the 1) disordered and 2) disordered and cold-worked states is measured as a function of ageing temperature and time. A number of microstructural changes occur on ageing and these result in complex ageing time-temperature dependences of the resistivity. It is found that the changes that lead to an increase in resistivity are (i) the initial stages of ordering and (ii) vanadium segregation, whereas the later stages of ordering, domain growth, recovery, and γ-phase precipitation are accompanied by a decrease in resistivity. (author)

  14. Noble metal alloys for metal-ceramic restorations.

    Science.gov (United States)

    Anusavice, K J

    1985-10-01

    A review of the comparative characteristics and properties of noble metal alloys used for metal-ceramic restorations has been presented. Selection of an alloy for one's practice should be based on long-term clinical data, physical properties, esthetic potential, and laboratory data on metal-ceramic bond strength and thermal compatibility with commercial dental porcelains. Although gold-based alloys, such as the Au-Pt-Pd, Au-Pd-Ag, and Au-Pd classes, may appear to be costly compared with the palladium-based alloys, they have clearly established their clinical integrity and acceptability over an extended period of time. Other than the relatively low sag resistance of the high gold-low silver content alloys and the potential thermal incompatibility with some commercial porcelain products, few clinical failures have been observed. The palladium-based alloys are less costly than the gold-based alloys. Palladium-silver alloys require extra precautions to minimize porcelain discoloration. Palladium-copper and palladium-cobalt alloys may also cause porcelain discoloration, as copper and cobalt are used as colorants in glasses. The palladium-cobalt alloys are least susceptible to high-temperature creep compared with all classes of noble metals. Nevertheless, insufficient clinical data exist to advocate the general use of the palladium-copper and palladium-cobalt alloys at the present time. One should base the selection and use of these alloys in part on their ability to meet the requirements of the ADA Acceptance Program. A list of acceptable or provisionally acceptable alloys is available from the American Dental Association and is published annually in the Journal of the American Dental Association. Dentists have the legal and ethical responsibility for selection of alloys used for cast restorations. This responsibility should not be delegated to the dental laboratory technician. It is advisable to discuss the criteria for selection of an alloy with the technician and the

  15. Bioactive glass–ceramic coating for enhancing the in vitro corrosion resistance of biodegradable Mg alloy

    International Nuclear Information System (INIS)

    Ye Xinyu; Cai Shu; Dou Ying; Xu Guohua; Huang Kai; Ren Mengguo; Wang Xuexin

    2012-01-01

    Highlights: ► Sol–gel derived 45S5 glass–ceramic coating was prepared on Mg alloy substrate. ► The corrosion resistance of glass–ceramic coated Mg alloy was markedly improved. ► The corrosion behavior of the coated sample varied due to the cracking of coating. - Abstract: In this work, a bioactive 45S5 glass–ceramic coating was synthesized on magnesium (Mg) alloy substrate by using a sol–gel dip-coating method, to improve the initial corrosion resistance of AZ31 Mg alloy. The surface morphology and phase composition of the glass–ceramic coating were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). The coating composed of amorphous phase and crystalline phase Na 2 Ca 2 Si 3 O 9 , with the thickness of ∼1.0 μm, exhibited a uniform and crack-free surface morphology. The corrosion behavior of the uncoated and coated Mg alloy substrates was investigated by the electrochemical measurements and immersion tests in simulated body fluid (SBF). Potentiodynamic polarization tests recorded an increase of potential (E corr ) form −1.60 V to −1.48 V, and a reduction of corrosion current density (i corr ) from 4.48 μA cm −2 to 0.16 μA cm −2 , due to the protection provided by the glass–ceramic coating. Immersion tests also showed the markedly improved corrosion resistance of the coated sample over the immersion period of 7 days. Moreover, after 14 days of immersion in SBF, the corrosion resistance of the coated sample declined due to the cracking of the glass–ceramic coating, which was confirmed by electrochemical impedance spectroscopy (EIS) analysis. The results suggested that the 45S5 glass–ceramic coated Mg alloy could provide a suitable corrosion behavior for use as degradable implants.

  16. Improving Corrosion Resistance and Biocompatibility of Magnesium Alloy by Sodium Hydroxide and Hydrofluoric Acid Treatments

    Directory of Open Access Journals (Sweden)

    Chang-Jiang Pan

    2016-12-01

    Full Text Available Owing to excellent mechanical property and biodegradation, magnesium-based alloys have been widely investigated for temporary implants such as cardiovascular stent and bone graft; however, the fast biodegradation in physiological environment and the limited surface biocompatibility hinder their clinical applications. In the present study, magnesium alloy was treated by sodium hydroxide (NaOH and hydrogen fluoride (HF solutions, respectively, to produce the chemical conversion layers with the aim of improving the corrosion resistance and biocompatibility. The results of attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR and X-ray photoelectron spectroscopy (XPS indicated that the chemical conversion layers of magnesium hydroxide or magnesium fluoride were obtained successfully. Sodium hydroxide treatment can significantly enhance the surface hydrophilicity while hydrogen fluoride treatment improved the surface hydrophobicity. Both the chemical conversion layers can obviously improve the corrosion resistance of the pristine magnesium alloy. Due to the hydrophobicity of magnesium fluoride, HF-treated magnesium alloy showed the relative better corrosion resistance than that of NaOH-treated substrate. According to the results of hemolysis assay and platelet adhesion, the chemical surface modified samples exhibited improved blood compatibility as compared to the pristine magnesium alloy. Furthermore, the chemical surface modified samples improved cytocompatibility to endothelial cells, the cells had better cell adhesion and proliferative profiles on the modified surfaces. Due to the excellent hydrophilicity, the NaOH-treated substrate displayed better blood compatibility and cytocompatibility to endothelial cells than that of HF-treated sample. It was considered that the method of the present study can be used for the surface modification of the magnesium alloy to enhance the corrosion resistance and biocompatibility.

  17. The Enhancement of Mg Corrosion Resistance by Alloying Mn and Laser-Melting

    Directory of Open Access Journals (Sweden)

    Youwen Yang

    2016-03-01

    Full Text Available Mg has been considered a promising biomaterial for bone implants. However, the poor corrosion resistance has become its main undesirable property. In this study, both alloying Mn and laser-melting were applied to enhance the Mg corrosion resistance. The corrosion resistance, mechanical properties, and microstructure of rapid laser-melted Mg-xMn (x = 0–3 wt % alloys were investigated. The alloys were composed of dendrite grains, and the grains size decreased with increasing Mn. Moreover, Mn could dissolve and induce the crystal lattice distortion of the Mg matrix during the solidification process. Mn ranging from 0–2 wt % dissolved completely due to rapid laser solidification. As Mn contents further increased up to 3 wt %, a small amount of Mn was left undissolved. The compressive strength of Mg-Mn alloys increased first (up to 2 wt % and then decreased with increasing Mn, while the hardness increased continuously. The refinement of grains and the increase in corrosion potential both made contributions to the enhancement of Mg corrosion resistance.

  18. Electrical resistivity of NaPb compound-forming liquid alloy using ab ...

    Indian Academy of Sciences (India)

    The study of electrical resistivity of compound-forming liquid alloy, NaPb, is presented as a function of concentration. Hard sphere diameters of Na and Pb are obtained through the interionic pair potentials evaluated using Troullier and Martins ab initio pseudopotential, which have been used to calculate the partial structure ...

  19. Corrosion resistant Zn–Co alloy coatings deposited using saw-tooth ...

    Indian Academy of Sciences (India)

    Administrator

    Keywords. Composition modulated multilayer alloy; Zn–Co; saw-tooth current pulse; corrosion resistance; dielectric spectroscopy. 1. ... capital cost and high energy cost an alternative method is required. Electrolytic deposition has ... cathode c.d., agitation, temperature, etc, the composition can be better controlled with great ...

  20. The Effect of Microstructure on the Abrasion Resistance of Low Alloyed Steels

    NARCIS (Netherlands)

    Xu, X.

    2016-01-01

    The thesis attempts to develop advanced high abrasion resistant steels with low hardness in combination with good toughness, processability and low alloying additions. For this purpose, a novel multi-pass dual-indenter (MPDI) scratch test approach has been developed to approach the real continuous

  1. Factors Affecting the Hydrogen Environment Assisted Cracking Resistance of an Al-Zn-Mg-(Cu) Alloy

    Energy Technology Data Exchange (ETDEWEB)

    G.A. Young; J.R. Scully

    2001-09-12

    It is well established that Al-Zn-Mg-(Cu) aluminum alloys are susceptible to hydrogen environment assisted cracking (HEAC) when exposed to aqueous environments. In Al-Zn-Mg-Cu alloys, overaged tempers are commonly used to increase HEAC resistance at the expense of strength. Overaging has little benefit in low copper alloys. However, the mechanism or mechanisms by which overaging imparts HEAC resistance is poorly understood. The present research investigated hydrogen uptake, diffusion, and crack growth rate in 90% relative humidity (RH) air for both a commercial copper bearing Al-Zn-Mg-Cu alloy (AA 7050) and a low copper variant of this alloy in order to better understand the factors which affect HEAC resistance. Experimental methods used to evaluate hydrogen concentrations local to a surface and near a crack tip include nuclear reaction analysis (NRA), focused ion beam, secondary ion mass spectroscopy (FIB/SIMS) and thermal desorption spectroscopy (TDS). When freshly bared coupons of AA 7050 are exposed to 90 C, 90% RH air, hydrogen ingress follows inverse-logarithmic-type kinetics and is equivalent for underaged (HEAC susceptible) and overaged (HEAC resistant) tempers. However, when the native oxide is allowed to form (24 hrs in 25 C, 40% RH lab air) prior to exposure to 90 C, 90% RH air, underaged alloy shows significantly greater hydrogen ingress than the overaged alloy. Humid air is a very aggressive environment producing local ({approx}1{micro}m) hydrogen concentrations in excess of 10,000 wt. ppm at 90 C. In the copper bearing alloy, overaging also effects the apparent diffusivity of hydrogen. As AA 7050 is aged from underaged {yields} peak aged {yields} overaged, the activation energy for hydrogen diffusion increases and the apparent diffusivity for hydrogen decreases, In the low copper alloy, overaging has little effect on hydrogen diffusion. Comparison of the apparent activation energies for hydrogen diffusion and for K independent (stage II) crack growth

  2. Effect of cold working and applied stress on the stress corrosion cracking resistance of nickel-chromium-iron alloys

    International Nuclear Information System (INIS)

    Yonezawa, T.; Onimura, K.; Itoh, H.; Saito, I.; Takamatsu, H.; Fujitani, T.

    1992-01-01

    In order to grasp the stress corrosion cracking quantitative resistance of Alloys 600 and 690 in PWR primary water, the authors have studied the effect of cold working and applied stress on the stress corrosion cracking resistance of Alloys 600 and 690, in high temperature water. Stress corrosion cracking tests were conducted at 360 degrees C (633K) in a simulated PWR primary water for about 12,000 hours or 24,000 hours. From the test results, it is concluded that the stress corrosion cracking resistance in the cold worked Alloy 600 at the same applied stress level increases with an increase in cold working ratio, and the cold worked Alloys of thermally treated 690 have the excellent stress corrosion cracking resistance. Further, in this paper, the planning of stress corrosion cracking test for weld joints and weld metal of Alloy 600 is described

  3. Corrosion resistance and surface characterization of electrolyzed Ti-Ni alloy.

    Science.gov (United States)

    Fukushima, Osamu; Yoneyama, Takayuki; Doi, Hisashi; Hanawa, Takao

    2006-03-01

    Ti-Ni alloy has been increasingly applied to medical and dental devices, such as coronary stents and orthodontic wires. This alloy contains nickel, which is known to give rise to cytotoxicity, metal allergy, and carcinogenicity. Therefore, the purpose of this study was to improve the corrosion resistance of Ti-Ni alloy by electrolytic treatment, whereby investigation was carried out using different acidic electrolyte compositions. As a result, specimens electrolyzed with lactic acid, water, and glycerol were found to show higher corrosion potential and release lower amount of titanium and nickel ions than mechanical-polished specimens (pnickel concentration in the surface oxide layer of Ti-Ni alloy decreased, and the thickness of the surface oxide layer increased. Based on the results of this study, it was shown that electrolytic treatment with suitable electrolyte could improve the corrosion resistance of Ti-Ni alloy, which is effective to produce medical and dental devices that utilize shape memory effect or superelasticity with better biocompatibility.

  4. Thermal Aging Effect on Corrosion Resistance in Fusion Boundary of A533 Gr. B and Alloy 152

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Kyoung Joon; Yoo, Seung Chang; Kim, Taeho; Ham, Junhyuk; Kim, Ji Hyun [UNIST, Ulsan (Korea, Republic of)

    2016-10-15

    Dissimilar metal weldment (DMW) is frequently used for joining low-alloy steel pressure vessel nozzles and steam generator nozzles to nickel-based wrought alloy or austenitic stainless steel components in high energy systems. This feature also significantly hinders C diffusion from the ferrite base metal to the weld metal. Until now, stress corrosion cracking has not occurred in DMWs where a High-Cr weld metal (such as Alloy 152 or Alloy 690), which is Ni-base weld metal including relative high Cr, is used as the weld metal in the weld between the nickel-based alloy and low-alloy steel. To understand the microstructure and corrosion evolution on fusion boundary between low-alloy steel and Ni-base weld metal, microstructural analysis and polarization test were performed with A533 Gr. B/Alloy 152/Alloy 690. Remarkable changes were observed in corrosion resistance and hardness at fusion boundary between low-alloy steel and Ni-base weld metal. The precipitate, which has different potential with peripheral region, can cause galvanic corrosion or pitting corrosion and is the one of hardening methods by disturbing movement of the dislocation. At initial step of heat treatment, the number of precipitates was increased. In fusion boundary between A533 Gr. B and Alloy 152, the corrosion resistance was decreased, and the hardness was increased. Next, at further step, the number of precipitates.

  5. Design of model alloys for martensitic/ferritic super heat-resistant 650 C steels

    Energy Technology Data Exchange (ETDEWEB)

    Knezevic, V.; Vilk, J.; Inden, G.; Sauthoff, G.; Agamennone, R.; Blum, W.

    2001-07-01

    The key to high creep strength of steels, besides solid solution strengthening, are fine distributions of stable precipitates which block the movement of subgrain boundaries and dislocations and delay coarsening of microstructure. The aim of the present study is to design new super heat-resistant 12%Cr ferritic steels using basic principles and concepts of physical metallurgy, to test and optimise model alloys and to investigate and clarify their behaviour under long-term creep conditions with emphasis on microstructural stability. Taking into consideration recent world-wide developments of 9-12%Cr steels with screening of available data, a series of model alloys is designed, which is supported by theoretical calculations and simulations of the expected phase transformations and precipitation processes. The alloys are prepared and tested mechanically. The effects of different types of precipitates as well as alloying elements on mechanical long-term properties are investigated. In particular the Laves phase is studied, which precipitates during service and which is to strengthen the alloys when M{sub 23}C{sub 6} precipitate particles besides finely distributed other carbides and nitrides become less effective. The effects of various austenite-forming alloying elements are also studied. (orig.)

  6. Use of Supplemental Short Pre-Contoured Accessory Rods and Cobalt Chrome Alloy Posterior Rods Reduces Primary Rod Strain and Range of Motion Across the Pedicle Subtraction Osteotomy Level

    DEFF Research Database (Denmark)

    Hallager, Dennis Winge; Gehrchen, Poul Martin; Dahl, Benny

    2016-01-01

    STUDY DESIGN: In vitro cadaveric biomechanical study. OBJECTIVE: To assess effects of 4-rod reconstruction, rod material, and anterior column support on motion and surface rod strain in a pedicle subtraction osteotomy model. SUMMARY OF BACKGROUND DATA: Pedicle subtraction osteotomy (PSO) can...... correct significant sagittal deformity of the lumbar spine; however, revision rates are high. To reduce rod strain and the incidence of rod fracture, clinical use of multi-rod construction, cobalt chrome (CoCr) alloy rods, and interbody spacers adjacent to PSO has been proposed. Investigating both motion...

  7. Effects of organic acid pickling on the corrosion resistance of magnesium alloy AZ31 sheet

    DEFF Research Database (Denmark)

    Nwaogu, Ugochukwu Chibuzoh; Blawert, C.; Scharnagl, N.

    2010-01-01

    Organic acids were used to clean AZ31 magnesium alloy sheet and the effect of the cleaning processes on the surface condition and corrosion performance of the alloy was investigated. Organic acid cleanings reduced the surface impurities and enhanced the corrosion resistance. Removal of at least 4...... mu m of the contaminated surface was required to reach corrosion rates less than 1 mm/year in salt spray condition. Among the three organic acids examined, acetic acid is the best choice. Oxalic acid can be an alternative while citric acid is not suitable for cleaning AZ31 sheet, because...

  8. Corrosion-resistant amorphous metallic films of Mo49Cr33B18 alloy

    Science.gov (United States)

    Ramesham, R.; Distefano, S.; Fitzgerald, D.; Thakoor, A. P.; Khanna, S. K.

    1987-01-01

    Corrosion-resistant amorphous metallic alloy films of Mo49Cr33B18 with a crystallization temperature of 590 C were deposited onto glass and quartz substrates by magnetron sputter-quench technique. The amorphous nature of the films was confirmed by their diffuse X-ray diffraction patterns. The deposited films are densely packed (zone T) and exhibit low stress and good adhesion to the substrate. Corrosion current of as-deposited coating of MoCrB amorphous metallic alloy is approximately three orders of magnitude less than the corrosion current of 304 stainless steel in 1N H2SO4 solution.

  9. Improved corrosion resistance of AZ91D magnesium alloy by a zinc–yttrium coating

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Hongxia; Yu, Bin; Wang, Weiwei [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China); Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Ministry of Education, Taiyuan, Shanxi 030024 (China); Ren, Guangxiao [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China); Liang, Wei, E-mail: liangwei@tyut.edu.cn [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China); Key Laboratory of Interface Science and Engineering in Advanced Materials, Taiyuan University of Technology, Ministry of Education, Taiyuan, Shanxi 030024 (China); Zhang, Jinshan [College of Materials Science and Engineering, Taiyuan University of Technology, Taiyuan, Shanxi 030024 (China)

    2014-01-05

    Highlights: • A zinc–yttrium coating can be formed on the surface of AZ91D magnesium alloy. • The coating contains a large amount of intermetallic compound Mg{sub 5}Al{sub 2}Zn{sub 2}. • The microhardness values of the coating are much higher than that of the substrate. • The coating can improve the corrosion resistance of the substrate effectively. -- Abstract: A zinc–yttrium coating on AZ91D magnesium alloy was conducted by diffusion treatment in order to improve its corrosion resistance and wear resistance. The microstructures and phase constituents of the zinc–yttrium coating were investigated using optical microscope (OM), X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive spectrum (EDS). The results reveal that a zinc–yttrium coating has been formed on the surface of magnesium specimens by the solidification of the liquid layer formed between the AZ91D magnesium alloy and the Zn, Y mixed powders. The microstructure of the zinc–yttrium coating is typical eutectic structure, which contains a large amount of intermetallic compound, such as Mg{sub 5}Al{sub 2}Zn{sub 2}. In addition, the microhardness values of the intermetallic compounds are much higher than those of the substrate and this would greatly contribute to the enhancement of wear resistance. The results of electrochemical corrosion tests in 3.5 wt.% NaCl solution show that the corrosion resistance of the coated specimens has been increased significantly.

  10. Improvement of corrosion resistance of low-alloy steels by resurfacing using multifunction cavitation in water

    Science.gov (United States)

    Ijiri, Masataka; Yoshimura, Toshihiko

    2018-02-01

    Low-alloy steels are based on carbon steel in combination with several percent or less (in many cases, 1 mass%) alloying elements, and they offer improved resistance to corrosion at a cost slightly higher than that of carbon steel. However, these materials do not exhibit the same corrosion resistance as stainless steel. The authors have previously developed a novel multifunction cavitation (MFC) technique, which combines ultrasonic cavitation with water jet cavitation. In this study, MFC was used to modify the surface of Cr-Mo steel (SCM435) and Ni-Cr-Mo steel (SNCM630). MFC was found to improve the residual stress value of the material as the result of surface modification while also imparting high strength and superior corrosion resistance.

  11. The Influence of Casting Defects on Fatigue Resistance of Elektron 21 Magnesium Alloy

    Directory of Open Access Journals (Sweden)

    Pikos I.

    2013-06-01

    Full Text Available The Mg-RE alloys are attractive, constructional materials, especially for aircraft and automotive industry, thanks to combination of low density, good mechanical properties, also at elevated temperature, and good castability and machinability. Present paper contains results of fatigue resistance test carried out on Elektron 21 magnesium alloy, followed by microstructural and fractographical investigation of material after test. The as-cast material has been heat treated according to two different procedures. The fatigue resistance test has been conducted with 106 cycles of uniaxial, sine wave form stress between 9 MPa and 90 MPa. Fractures of specimens, which ruptured during the test, have been investigated with scanning electron microscope. The microstructure of specimens has been investigated with light microscopy. Detrimental effect of casting defects, as inclusions and porosity, on fatigue resistance has been proved. Also the influence of heat treatment's parameters has been described.

  12. Microstructure and corrosion resistance of phytic acid conversion coatings for magnesium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Cui Xiufang [School of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Li Qingfen [School of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China); Li Ying; Wang Fuhui [State Key Laboratory for Corrosion and Protection, Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Jin Guo [School of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)], E-mail: jg97721@yahoo.com.cn; Ding Minghui [School of Materials Science and Chemical Engineering, Harbin Engineering University, Harbin 150001 (China)

    2008-12-30

    In this paper, a new innoxious and pollution-free chemical protective coating for magnesium alloys, phytic acid conversion coating, was prepared. The conversion coatings are found to have high cover ratio and no cracks are found by atomic force microscopes (AFM) and scanning electron microscopy (SEM). The main elements of the conversion coatings are Mg, Al, O, P and C by X-ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The chemical state of the elements in the coatings was also investigated by Fourier transform infrared spectroscopy (FTIR). AES depth profile analysis suggests that the thickness of the conversion coating is about 340 nm. The corrosion resistance of the coatings was evaluated by polarization curves. The results indicate that the corrosion resistance for the conversion coated AZ91D magnesium alloys in 3.5% NaCl solution increases markedly. The mechanisms of corrosion resistance and coatings formation are also discussed.

  13. Multiscale Electrochemical Investigation of the Corrosion Resistance of Various Alloys Used in Dental Prostheses

    Science.gov (United States)

    Iacoban, Sorin; Mareci, Daniel; Bolat, Georgiana; Munteanu, Corneliu; Souto, Ricardo Manuel

    2015-04-01

    The electrochemical behavior of Ag-Pd (Paliag), Ni-Cr (Heraenium NA), and Co-Cr (Heraenium CE) alloys used in dental prosthetics construction of crowns and bridges was studied in 0.9 pct NaCl solution at 298 K (25 °C). The localized electrochemical characteristics related to corrosion resistance and eventual breakdown of the protecting oxide layers were investigated by scanning electrochemical microscopy (SECM), whereas potentiodynamic polarization and electrochemical impedance spectroscopy techniques were employed to establish oxide stability. When the corrosion resistance of the alloys was evaluated by means of the corrosion current value determined around their corresponding open circuit potential in 0.9 pct NaCl solution, good protection can be expected resulting from their spontaneous passivation (low current densities in the order of tenths of μA cm-2). The polarization resistance of all the samples increased with immersion time, in the sequence Ag-Pd Ag-Pd instead.

  14. Evaluation of High Temperature Corrosion Resistance of Finned Tubes Made of Austenitic Steel And Nickel Alloys

    Directory of Open Access Journals (Sweden)

    Turowska A.

    2016-06-01

    Full Text Available The purpose of the paper was to evaluate the resistance to high temperature corrosion of laser welded joints of finned tubes made of austenitic steel (304,304H and nickel alloys (Inconel 600, Inconel 625. The scope of the paper covered the performance of corrosion resistance tests in the atmosphere of simulated exhaust gases of the following chemical composition: 0.2% HCl, 0.08% SO2, 9.0% O2 and N2 in the temperature of 800°C for 1000 hours. One found out that both tubes made of austenitic steel and those made of nickel alloy displayed good resistance to corrosion and could be applied in the energy industry.

  15. Cobalt: for strength and color

    Science.gov (United States)

    Boland, Maeve A.; Kropschot, S.J.

    2011-01-01

    Cobalt is a shiny, gray, brittle metal that is best known for creating an intense blue color in glass and paints. It is frequently used in the manufacture of rechargeable batteries and to create alloys that maintain their strength at high temperatures. It is also one of the essential trace elements (or "micronutrients") that humans and many other living creatures require for good health. Cobalt is an important component in many aerospace, defense, and medical applications and is a key element in many clean energy technologies. The name cobalt comes from the German word kobold, meaning goblin. It was given this name by medieval miners who believed that troublesome goblins replaced the valuable metals in their ore with a substance that emitted poisonous fumes when smelted. The Swedish chemist Georg Brandt isolated metallic cobalt-the first new metal to be discovered since ancient times-in about 1735 and identified some of its valuable properties.

  16. In vitro profiling of epigenetic modifications underlying heavy metal toxicity of tungsten-alloy and its components

    International Nuclear Information System (INIS)

    Verma, Ranjana; Xu, Xiufen; Jaiswal, Manoj K.; Olsen, Cara; Mears, David; Caretti, Giuseppina; Galdzicki, Zygmunt

    2011-01-01

    Tungsten-alloy has carcinogenic potential as demonstrated by cancer development in rats with intramuscular implanted tungsten-alloy pellets. This suggests a potential involvement of epigenetic events previously implicated as environmental triggers of cancer. Here, we tested metal induced cytotoxicity and epigenetic modifications including H3 acetylation, H3-Ser10 phosphorylation and H3-K4 trimethylation. We exposed human embryonic kidney (HEK293), human neuroepithelioma (SKNMC), and mouse myoblast (C2C12) cultures for 1-day and hippocampal primary neuronal cultures for 1-week to 50-200 μg/ml of tungsten-alloy (91% tungsten/6% nickel/3% cobalt), tungsten, nickel, and cobalt. We also examined the potential role of intracellular calcium in metal mediated histone modifications by addition of calcium channel blockers/chelators to the metal solutions. Tungsten and its alloy showed cytotoxicity at concentrations > 50 μg/ml, while we found significant toxicity with cobalt and nickel for most tested concentrations. Diverse cell-specific toxic effects were observed, with C2C12 being relatively resistant to tungsten-alloy mediated toxic impact. Tungsten-alloy, but not tungsten, caused almost complete dephosphorylation of H3-Ser10 in C2C12 and hippocampal primary neuronal cultures with H3-hypoacetylation in C2C12. Dramatic H3-Ser10 dephosphorylation was found in all cobalt treated cultures with a decrease in H3 pan-acetylation in C2C12, SKNMC and HEK293. Trimethylation of H3-K4 was not affected. Both tungsten-alloy and cobalt mediated H3-Ser10 dephosphorylation were reversed with BAPTA-AM, highlighting the role of intracellular calcium, confirmed with 2-photon calcium imaging. In summary, our results for the first time reveal epigenetic modifications triggered by tungsten-alloy exposure in C2C12 and hippocampal primary neuronal cultures suggesting the underlying synergistic effects of tungsten, nickel and cobalt mediated by changes in intracellular calcium homeostasis and

  17. Burner rig alkali salt corrosion of several high temperature alloys

    Science.gov (United States)

    Deadmore, D. L.; Lowell, C. E.

    1977-01-01

    The hot corrosion of five alloys was studied in cyclic tests in a Mach 0.3 burner rig into whose combustion chamber various aqueous salt solutions were injected. Three nickel-based alloys, a cobalt-base alloy, and an iron-base alloy were studied at temperatures of 700, 800, 900, and 1000 C with various salt concentrations and compositions. The relative resistance of the alloys to hot corrosion attack was found to vary with temperature and both concentration and composition of the injected salt solution. Results indicate that the corrosion of these alloys is a function of both the presence of salt condensed as a liquid on the surface and of the composition of the gas phases present.

  18. Fatigue Crack-Growth Resistance of Aluminum Alloys Under Spectrum Loading. Volume 2. Aluminum Lithium Alloys.

    Science.gov (United States)

    1985-12-01

    Bretz (Alcoa) 13a. TYPE OF REPORT 13b. TIME COVERED 14 DATE OF REPORT IYr . Mo.. Daye IS. PAGE COUNT Technical Report FROM 30Segt82 TO _1 Ma85 DECEMBER...alloy for both constant-amplitude loading and two F-18 load spectrums. One of the spectrums was dominated by tension loads ( TD ) and the other spectrum...indicating contact between the opposing fracture surfaces. Several observations can be made based on the TD and TC spectrum FCP test results: 1. The fatigue

  19. Effects of as-cast and wrought Cobalt-Chrome-Molybdenum and Titanium-Aluminium-Vanadium alloys on cytokine gene expression and protein secretion in J774A.1 macrophages

    DEFF Research Database (Denmark)

    Jakobsen, Stig Storgaard; Larsen, Agnete; Stoltenberg, Meredin

    2007-01-01

    the cell viability. Surface properties of the discs were characterised with a profilometer and with energy dispersive X-ray spectroscopy. We here report, for the first time, that the prosthetic material surface (non-phagocytable) of as-cast high carbon CoCrMo reduces the pro-inflammatory cytokine IL-6......Insertion of metal implants is associated with a possible change in the delicate balance between pro- and anti-inflammatory proteins, probably leading to an unfavourable predominantly pro-inflammatory milieu. The most likely cause is an inappropriate activation of macrophages in close relation...... to the metal implant and wear-products. The aim of the present study was to compare surfaces of as-cast and wrought Cobalt-Chrome-Molybdenum (CoCrMo) alloys and Titanium-Aluminium-Vanadium (TiAlV) alloy when incubated with mouse macrophage J774A.1 cell cultures. Changes in pro- and anti-inflammatory cytokines...

  20. Corrosion resistance of a composite polymeric coating applied on biodegradable AZ31 magnesium alloy.

    Science.gov (United States)

    Zomorodian, A; Garcia, M P; Moura e Silva, T; Fernandes, J C S; Fernandes, M H; Montemor, M F

    2013-11-01

    The high corrosion rate of magnesium alloys is the main drawback to their widespread use, especially in biomedical applications. There is a need for developing new coatings that provide simultaneously corrosion resistance and enhanced biocompatibility. In this work, a composite coating containing polyether imide, with several diethylene triamine and hydroxyapatite contents, was applied on AZ31 magnesium alloys pre-treated with hydrofluoric acid by dip coating. The coated samples were immersed in Hank's solution and the coating performance was studied by electrochemical impedance spectroscopy and scanning electron microscopy. In addition, the behavior of MG63 osteoblastic cells on coated samples was investigated. The results confirmed that the new coatings not only slow down the corrosion rate of AZ31 magnesium alloys in Hank's solution, but also enhance the adhesion and proliferation of MG63 osteoblastic cells, especially when hydroxyapatite nanoparticles were introduced in the coating formulation. Copyright © 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

  1. Improving of wear resistance of alloys with metastable austenite structure in abrasion wearing

    International Nuclear Information System (INIS)

    Popov, V.S.; Brykov, N.N.; Pugachev, G.A.

    1979-01-01

    The effect of grain composition of abrasive masses upon the wear resistance of alloys having a metastable austenitic structure is studied. The investigations have been carried out on Kh12F1 steel, using diffraction and hardness measurements and the metallographic analysis. Experimental data indicate that the specific wear of the stable alloys increases substantially with the size of abrasive particles. As regards the metastable alloys, the increase in the size of the abrasive grains has little effect upon the specific wear, as the increasing abradability of the grains is compensated for by the strengthening of the rubbing surfaces, this resulting from the ability of the metal surface layer to underao structure transformations in the course of wear

  2. Influence of structural relaxation and partial devitrification on the corrosion resistance of Fe78B13Si9 amorphous alloy

    International Nuclear Information System (INIS)

    Souza, C.A.C.; Politi, F.S.; Kiminami, C.S.

    1998-01-01

    Amorphous alloys obtained by rapid solidification from the melt exhibit a similar structure to those observed in the liquid state, i.e., without long range ordering, in such a way that the constituents of the alloy usually are randomly and homogeneously distributed. Amorphous alloys, depending on their composition, may exhibit interesting characteristics such as very soft magnetic properties and improved resistance to corrosion. The high corrosion resistance of these alloys is attributed mainly to a higher rate of dissolution of passivating elements in the amorphous state. In addition, amorphous alloys are chemically homogeneous and free of defects such as grain boundaries, precipitates and segregation, which are favorable sites for corrosion. The corrosion resistance of amorphous alloys also depends on their thermal history. Several authors have reported that structural changes, such as structural relaxation and devitrification caused by annealing, change significantly the corrosion properties of these alloys. The purpose of this paper is to study corrosion resistance of the amorphous FeBSi alloy and the effects of structural changes such as structural relaxation and partial crystallization caused by annealing

  3. Corrosion resistance of titanium alloy on the overpack for high-level radioactive waste disposal

    International Nuclear Information System (INIS)

    Nishimura, Toshiyasu

    2008-01-01

    Crevice corrosion of titanium and its alloys were investigated in 10% sodium chloride at 100 degC simulating the environment of the overpack near the seaside. The pH and Chloride ion concentration inside the crevice were monitored by using W/WO 3 and Ag/AgCl microelectrode, respectively. The pH and Cl - concentration within the crevice were calculated from the standard potential-pH and potential-log [Cl - ] calibration curves. The effect of Mo on the crevice corrosion of titanium was mainly studied. The passivation behavior of the titanium and Ti-15% Mo alloy were also studied using electrochemical impedance studies. A marginal decrease in pH and increase in Cl - ion concentration were observed for pure titanium at 100 degC, where there was large increase of the crevice current. On other hand, there was no apparent change in pH and Cl - ion activity inside the crevice for Ti-15% Mo alloy, where there was no increase of the crevice current. Based on the results, it has been documented that the Ti-15% Mo alloy was not susceptible to crevice corrosion in 10% NaCl solutions at 100 degC. The corrosion reaction resistance (R t ) was found to increase with addition of Mo as an alloying element and also increase with applied anodic potential. Hence, Mo is able to be an effective alloying element, which enhanced the crevice corrosion resistance of titanium under the environment simulating the overpack near the seaside. (author)

  4. Cerium Addition Improved the Dry Sliding Wear Resistance of Surface Welding AZ91 Alloy

    Directory of Open Access Journals (Sweden)

    Qingqiang Chen

    2018-02-01

    Full Text Available In this study, the effects of cerium (Ce addition on the friction and wear properties of surface welding AZ91 magnesium alloys were evaluated by pin-on-disk dry sliding friction and wear tests at normal temperature. The results show that both the friction coefficient and wear rate of surfacing magnesium alloys decreased with the decrease in load and increase in sliding speed. The surfacing AZ91 alloy with 1.5% Ce had the lowest friction coefficient and wear rate. The alloy without Ce had the worst wear resistance, mainly because it contained a lot of irregularly shaped and coarse β-Mg17Al12 phases. During friction, the β phase readily caused stress concentration and thus formed cracks at the interface between β phase and α-Mg matrix. The addition of Ce reduced the size and amount of Mg17Al12, while generating Al4Ce phase with a higher thermal stability. The Al-Ce phase could hinder the grain-boundary sliding and migration and reduced the degree of plastic deformation of subsurface metal. Scanning electron microscopy observation showed that the surfacing AZ91 alloy with 1.5% Ce had a total of four types of wear mechanism: abrasion, oxidation, and severe plastic deformation were the primary mechanisms; delamination was the secondary mechanism.

  5. Biomimetic coating of magnesium alloy for enhanced corrosion resistance and calcium phosphate deposition.

    Science.gov (United States)

    Cui, W; Beniash, E; Gawalt, E; Xu, Z; Sfeir, C

    2013-11-01

    Degradable metals have been suggested as biomaterials with revolutionary potential for bone-related therapies. Of these candidate metals, magnesium alloys appear to be particularly attractive candidates because of their non-toxicity and outstanding mechanical properties. Despite their having been widely studied as orthopedic implants for bone replacement/regeneration, their undesirably rapid corrosion rate under physiological conditions has limited their actual clinical application. This study reports the use of a novel biomimetic peptide coating for Mg alloys to improve the alloy corrosion resistance. A 3DSS biomimetic peptide is designed based on the highly acidic, bioactive bone and dentin extracellular matrix protein, phosphophoryn. Surface characterization techniques (scanning electron microscopy, energy dispersive X-ray spectroscopy and diffuse-reflectance infrared spectroscopy) confirmed the feasibility of coating the biomimetic 3DSS peptide onto Mg alloy AZ31B. The 3DSS peptide was also used as a template for calcium phosphate deposition on the surface of the alloy. The 3DSS biomimetic peptide coating presented a protective role of AZ31B in both hydrogen evolution and electrochemical corrosion tests. Copyright © 2013. Published by Elsevier Ltd.

  6. Cerium Addition Improved the Dry Sliding Wear Resistance of Surface Welding AZ91 Alloy.

    Science.gov (United States)

    Chen, Qingqiang; Zhao, Zhihao; Zhu, Qingfeng; Wang, Gaosong; Tao, Kai

    2018-02-06

    In this study, the effects of cerium (Ce) addition on the friction and wear properties of surface welding AZ91 magnesium alloys were evaluated by pin-on-disk dry sliding friction and wear tests at normal temperature. The results show that both the friction coefficient and wear rate of surfacing magnesium alloys decreased with the decrease in load and increase in sliding speed. The surfacing AZ91 alloy with 1.5% Ce had the lowest friction coefficient and wear rate. The alloy without Ce had the worst wear resistance, mainly because it contained a lot of irregularly shaped and coarse β-Mg 17 Al 12 phases. During friction, the β phase readily caused stress concentration and thus formed cracks at the interface between β phase and α-Mg matrix. The addition of Ce reduced the size and amount of Mg 17 Al 12 , while generating Al₄Ce phase with a higher thermal stability. The Al-Ce phase could hinder the grain-boundary sliding and migration and reduced the degree of plastic deformation of subsurface metal. Scanning electron microscopy observation showed that the surfacing AZ91 alloy with 1.5% Ce had a total of four types of wear mechanism: abrasion, oxidation, and severe plastic deformation were the primary mechanisms; delamination was the secondary mechanism.

  7. Nanocontainer-Enhanced Self-Healing for Corrosion-Resistant Ni Coating on Mg Alloy.

    Science.gov (United States)

    Xie, Zhi-Hui; Li, Dan; Skeete, Zakiya; Sharma, Anju; Zhong, Chuan-Jian

    2017-10-18

    The ability to manipulate the functionalization of Ni coating is of great importance in improving the corrosion resistance of magnesium (Mg) alloy for many industrial applications. In the present work, MCM-41 type mesoporous silica nanocontainers (MSNs) loaded with corrosion inhibitor (NaF) were synthesized and employed as smart reinforcements to enhance the integrity and corrosion inhibition of the Ni coating. The incorporation of the F-loaded MSNs (F@MSNs) to enhance the corrosion resistant capacity of a metallic coating is reported for the first time. The mesoporous structures of the as-prepared MSNs and F@MSNs were confirmed by transmission electron microscopy (TEM), small angle X-rays scattering (SAXS), and N 2 adsorption-desorption isotherms. The X-ray photoelectron spectroscopy (XPS) data demonstrated the successful immobilization of fluoride ion on the MSNs and formation of a magnesium fluoride (MgF 2 ) protective film at the corrosion sites of the Mg alloy upon soaking in a F@MSNs-containing NaCl solution. The results from potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) for both bare Mg alloy and Ni coatings with and without F@MSNs have revealed a clear decrease in corrosion rate in a corrosive solution for a long-time immersion due to the introduction of F@MSNs. These findings open new opportunities in the exploration of self-healing metallic coatings for highly enhanced anticorrosion protection of Mg alloy.

  8. Study on fatigue resistance of low alloy steels with Mo and Cr

    Science.gov (United States)

    Enculescu, E.; Chicet, D. L.; Dia, V.; Stanciu, S.

    2016-08-01

    This paper presents, based on a case study, the analysis of the factors that influence the mechanical cyclic fatigue resistance of two grades of low alloy steel with Mo and Cr. It was studied the fatigue behavior in real operating conditions of some active elements manufactured from the two low-alloyed steel grades, elements that are equipping some farm implements. Using the fractographic analysis, optical microscopy and scanning electron microscopy, were analyzed the samples that carried away because of the fatigue fracture. On samples taken from the two brands of low alloy steels with Mo and Cr were performed tempering thermal treatments that modified the structure, in order to improve the operating characteristics. The effect of those thermal treatments was initially observed by microstructural analysis of metallographic prepared samples (by polishing and chemical attack using nital reagent), that revealed a troostite type structure. On the heat-treated samples were determined a number of mechanical properties: hardness, impact strength and tensile test. There was observed an improvement of the impact bending strength for both alloys and a tensile behavior that favors increasing resistance to fatigue.

  9. The role of solidification rate in the corrosion resistance of a directionally solidified novel aluminium-lanthanum alloy

    Energy Technology Data Exchange (ETDEWEB)

    Dzib-Perez, L. [Programa de Corrosion del Golfo de Mexico, Universidad Autonoma de Campeche, Av. Agustin Melgar s/n, Col. Buenavista, CP 24030 Campeche, Campeche (Mexico); Gonzalez-Sanchez, J. [Programa de Corrosion del Golfo de Mexico, Universidad Autonoma de Campeche, Av. Agustin Melgar s/n, Col. Buenavista, CP 24030 Campeche, Campeche (Mexico)]. E-mail: jagonzal@uacam.mx; Perez, T. [Programa de Corrosion del Golfo de Mexico, Universidad Autonoma de Campeche, Av. Agustin Melgar s/n, Col. Buenavista, CP 24030 Campeche, Campeche (Mexico); Bartolo-Perez, P. [Programa de Corrosion del Golfo de Mexico, Universidad Autonoma de Campeche, Av. Agustin Melgar s/n, Col. Buenavista, CP 24030 Campeche, Campeche (Mexico); CINVESTAV-Merida, Applied Physics Department, Carr. antigua a Progreso, km 6, CP 97310 Merida, Yucatan (Mexico); Juarez, A. [CIATEQ. Calzada del Retablo 150, CP 76150 Queretaro, Queretaro (Mexico)

    2006-08-15

    The corrosion resistance of a novel Al-12.6 wt.%La alloy manufactured using unidirectional solidification was studied by sensitive electrochemical techniques. It was found that the electrochemical behaviour of the alloy depends upon the formation of non-passive corrosion product layers. Different solidification rates produced dissimilar microstructures which promoted selective dissolution when the alloy was anodically polarized in distilled water. A model for the electrochemical behaviour of this alloy was proposed based on an equivalent circuit that simulated the impedance results.

  10. Experimental Study of Laser - enhanced 5A03 Aluminum Alloy and Its Stress Corrosion Resistance

    Science.gov (United States)

    Wang, Guicheng; Chen, Jing; Pang, Tao

    2018-02-01

    Based on the study of improving the stress corrosion resistance of 5A03 aluminum alloy for ship, this paper mainly studied the tensile test, surface morphology and residual stress under laser shock, high temperature and stress corrosion. It is found that the residual compressive stress and the grain refinement on the surface of the material during the heat strengthening process increase the breaking strength of the sample in the stress corrosion environment. Appropriate high temperature maintenance helps to enhance the effect of deformation strengthening. In the 300°C environment insulation, due to recrystallization of the material, the performance decreased significantly. This study provides an experimental basis for effectively improving the stress corrosion resistance of 5A03 aluminum alloy.

  11. INFLUENCE OF PHOSPHATIZED SURFACE LAYER ON CORROSION RESISTANCE OF Mg-Al-RE ALLOY

    Directory of Open Access Journals (Sweden)

    Katarína Miková

    2015-09-01

    Full Text Available This contribution deals with evaluation of the corrosion resistance of extruded Mg-2Al-1RE (AE21 magnesium alloy in the state before and after treatment of ground surface by selected phosphatizing procedure. Specimens were exposed to 0.1M NaCl solution for several time periods starting from 5 minutes up-to 168 hours at room temperature of 22 ± 1 °C. Afterwards electrochemical impedance spectroscopy was carried out on the exposed specimens. Based on the results obtained from the electrochemical tests and visual observation of corrosion attack progress, positive or negative impact of selected phosphating process on the corrosion resistance of Mg-2Al-1RE magnesium alloy under given conditions was assessed.

  12. Corrosion-resistant amorphous alloy ribbons for electromagnetic filtration of iron rusts from water

    International Nuclear Information System (INIS)

    Kawashima, Asahi; Asami, Katsuhiko; Sato, Takeaki; Hashimoto, Koji

    1985-01-01

    An attempt was made to use corrosion-resistant amorphous Fe-9Cr-13P-7C alloy ribbons as an electromagnetic filter material for trapping various iron rusts suspended in water at 40 0 C. The ferrimagnetic Fe 3 O 4 rust was trapped with the 100 % efficiency and paramagnetic rusts such as α-Fe 2 O 3 , α-FeOOH and amorphous ferric oxyhydroxide were trapped with certain efficiencies at the magnetic field strength of 0.5-10 kOe. The regeneration of the filter by back-washing was easy. The trapping capacity of electromagnetic filter was proportional to the edge length of the filter material where the high magnetic field strength existed. Therefore, melt-spun thin and narrow amorphous alloy ribbons having the high corrosion resistance have the potential utility as electromagnetic filter material. (author)

  13. Structure and electrical resistivity of alkali-alkali and lithium-based liquid binary alloys

    International Nuclear Information System (INIS)

    Mishra, A.K.; Mukherjee, K.K.

    1990-01-01

    Harmonic model potential, developed and used for simple metals is applied here to evaluate hardsphere diameters, which ensure minimum interionic pair potential for alkali-alkali (Na-K, Na-Rb, Na-Cs, K-Rb, K-Cs) and lithium-based (Li-Na, Li-Mg, Li-In, Li-Tl) liquid binary alloys as a function of composition for use in the determination of their partial structure factors. These structure factors are then used to calculate electrical resistivities of alloys considered. The computed values of electrical resistivity as a function of composition agree both, in magnitude and gradient reasonably well with experimental values in all cases except in Cs systems, where the disagreement is appreciable. (author)

  14. Increased resistance to stress corrosion of aluminum alloys

    Science.gov (United States)

    Brummer, S. B.; Cocks, F. H.

    1970-01-01

    Stress corrosion resistance is increased by distorting surface grain-boundary structure and by interrupting the corrosion and stress corrosion. The first is accomplished by machining or shot peening and the second by removal from and later reexposure to the corrosive environment.

  15. Thermophysical properties of selected wear-resistant alloys

    International Nuclear Information System (INIS)

    Farwick, D.G.; Johnson, R.N.

    1980-06-01

    Thermophysical properties of 13 selected wear-resistant materials, including specific heat, thermal conductivity, thermal diffusivity, and thermal expansion (instantaneous, mean, and linear) are provided. The Center for Information and Numerical Data Analysis and Synthesis (CINDAS) at Purdue University supplied properties data

  16. Alternative Zr alloys with irradiation resistant precipitates for high burnup BWR application

    International Nuclear Information System (INIS)

    Garzarolli, F.; Ruhmann, H.; Van Swan, L.

    2002-01-01

    In the core of BWRs, the second-phase particles (SPP) of Zircaloy-2 and Zircaloy-4, the Zr(FeCr) 2 and the Zr 2 (FeNi) phase, release Fe and dissolve. The degree of dissolution depends on initial size and fluence. These SPP, however, are important for the corrosion behavior of Zircaloy. Zircaloy shows an increase of corrosion at a certain burnup, depending on the initial SPP size and fast neutron fluence. Only Zr alloys with irradiation resistant SPP avoid this type of increased corrosion completely. Two types of irradiation resistant materials were considered. One is a Zr-Sn-Fe alloy containing the Zr 3 Fe phase, which is irradiation resistant under BWR conditions. The other material is a Zr-Sn-Nb alloy containing the irradiation resistant β-Nb phase. In-BWR tests have shown that a Sn content of >0.8% is mandatory to minimize the nodular corrosion. Two prototypes of irradiation resistant alloys, Zr1.3Sn0.25-0.3 Fe and Zr1Sn2-3Nb, were irradiated in a BWR for 1372 days to a fast fluence of 9 x 10 21 n/cm 2 (E > 1 MeV). These irradiation tests showed that Zr1.3Sn0.25-0.3 Fe has a little lower resistance against nodular corrosion than optimized LTP (Low Temperature Process) Zircaloy-2/4 and revealed that Zr1Sn2-3Nb is superior to LTP Zircaloy-2/4 with respect to nodular and shadow corrosion resistance. The BWR corrosion resistance of Zr1Sn2-3Nb depends on heat treatment. The lowest corrosion was observed with material fabricated completely in the α-range, but also material manufactured in the lower (α+β)-range exhibits low corrosion. Material fabricated in the upper (α+β)-range showed a somewhat higher corrosion, a corrosion behavior similar to LTP Zircaloy-2/4. As far as final annealing is concerned, a long time annealing at 540 deg C is superior to a standard recrystallization treatment (e.g., at 580 deg C), which still leads to a corrosion behavior that is better than stress relieved Zr1Sn2-3Nb. Zr1Sn2-3Nb is resistant to shadow corrosion, when fabricated

  17. Process for improving the corrosion resistance of zirconium alloy structure parts

    International Nuclear Information System (INIS)

    Hanneman, R.E.; Urquhart, A.W.; Vermilyea, D.A.

    1976-01-01

    A process is described for improving the corrosion resistance of zirconium alloy structure parts in the environment of BWR type reactors. It comprises the production on the structure parts of an adhesive film consisting of electron conducting and chemically inert materials in the conditions prevailing in the BWR type reactors. The film can be made of Au, Ag, Pt, Ni, Cr, Fe or Nb [fr

  18. Electrical resistivity of amorphous Fesub(1-x) Bsub(x) alloys

    International Nuclear Information System (INIS)

    Paja, A.; Stobiecki, T.

    1984-07-01

    The concentration dependence of the electrical resistivity of amorphous Fesub(1-x) Bsub(x) alloys has been studied over a broad composition range. The measurements for RF sputtered films made in the liquid helium temperature have been analyzed in the framework of the diffraction model. The calculated results are in good agreement with the experimental data in the range of concentration 0.12< x <0.37 where samples are amorphous and have a metallic character. (author)

  19. The Resistivity And Thermoelectric-Power Of Liquid Ag-Pd Alloys

    OpenAIRE

    Newport, Robert J.; Dupree, B.C.; Enderby, J.E.; Howe, R.A.

    1981-01-01

    The resistivity (ρ) and the thermoelectric power (S) have been measured as functions of concentration and temperature for the liquid alloy system Ag-Pd. Comparison is made between the experimental results and the theoretical predictions of a nearly free electron model adapted for liquid transition metals. It is concluded that such a theory is unable to reproduce the gross features of the concentration dependence of ρ and S even when concentration-dependent effective valencies are introduced. ...

  20. Spin disordered resistivity of the Heusler Ni.sub.2./sub.MnGa-based alloys

    Czech Academy of Sciences Publication Activity Database

    Kamarád, Jiří; Kaštil, Jiří; Albertini, F.; Fabbrici, S.; Arnold, Zdeněk

    2017-01-01

    Roč. 131, č. 4 (2017), s. 1072-1074 ISSN 0587-4246 R&D Projects: GA ČR GAP204/12/0692 Institutional support: RVO:68378271 Keywords : spin disordered resistivity * magnetoresistance * Heusler alloys * Ni 2 MnGa Subject RIV: BM - Solid Matter Physics ; Magnetism OBOR OECD: Condensed matter physics (including formerly solid state physics, supercond.) Impact factor: 0.469, year: 2016

  1. Chemical passivation as a method of improving the electrochemical corrosion resistance of Co-Cr-based dental alloy.

    Science.gov (United States)

    Rylska, Dorota; Sokołowski, Grzegorz; Sokołowski, Jerzy; Łukomska-Szymańska, Monika

    2017-01-01

    The purpose of the study was to evaluate corrosion resistance of Wirobond C® alloy after chemical passivation treatment. The alloy surface undergone chemical passivation treatment in four different media. Corrosion studies were carried out by means of electrochemical methods in saline solution. Corrosion effects were determined using SEM. The greatest increase in the alloy polarization resistance was observed for passive layer produced in Na2SO4 solution with graphite. The same layer caused the highest increase in corrosion current. Generally speaking, the alloy passivation in Na2SO4 solution with graphite caused a substantial improvement of the corrosion resistance. The sample after passivation in Na2SO4 solution without graphite, contrary to others, lost its protective properties along with successive anodic polarization cycles. The alloy passivation in Na3PO4 solution with graphite was the only one that caused a decrease in the alloy corrosion properties. The SEM studies of all samples after chemical passivation revealed no pit corrosion - in contrast to the sample without any modification. Every successive polarization cycle in anodic direction of pure Wirobond C® alloy enhances corrosion resistance shifting corrosion potential in the positive direction and decreasing corrosion current value. The chemical passivation in solutions with low pH values decreases susceptibility to electrochemical corrosion of Co-Cr dental alloy. The best protection against corrosion was obtained after chemical passivation of Wirobond C® in Na2SO4 solution with graphite. Passivation with Na2SO4 in solution of high pH does not cause an increase in corrosion resistance of WIROBOND C. Passivation process increases alloy resistance to pit corrosion.

  2. Irreversibility in transformation behavior of equiatomic nickel-titanium alloy by electrical resistivity measurement

    International Nuclear Information System (INIS)

    Matsumoto, Hitoshi

    2004-01-01

    Measurements of the electrical resistivity were precisely performed on shape memory Ni 50 Ti 50 alloy in order to reveal the irreversible behavior of the thermoelastic martensitic transformation with thermal cycling. The hump in the electrical resistivity during cooling is enhanced with increasing the number of complete thermal cycles to result in a peak, although no peak in the electrical resistivity is observed on the reverse transformation during heating. The electrical resistivity in the low-temperature phase, of which the temperature dependence is linear, increases with increasing the number of complete thermal cycles. The temperature coefficient of the electrical resistivity in the temperature region of the high-temperature phase increases with elevating the temperature. The transformation is strongly influenced by incomplete thermal cycles to result in a peak in the resistivity even on the reverse transformation after incomplete thermal cycling. It is thought that the anomalous behavior such as enhancement of a resistivity-peak, the increase in the electrical resistivity of the low-temperature phase, and the nonlinear relation between the resistivity and the temperature in the high-temperature phase are attributable to the appearance of an intermediate phase stabilized by transformation-induced defects, the accumulation of the transformation-induced defects, and the electron scattering due to the softening of a phonon mode in the high-temperature phase, respectively. It proved useful to make more accurate measurements of the electrical resistivity in order to investigate the intrinsic behavior of the transformation in NiTi

  3. Corrosion resistance of materials of construction for high temperature sulfuric acid service in thermochemical IS process. Alloy 800, Alloy 600, SUSXM15J1 and SiC

    International Nuclear Information System (INIS)

    Tanaka, Nobuyuki; Onuki, Kaoru; Shimizu, Saburo; Yamaguchi, Akihisa

    2006-01-01

    Exposure tests of candidate materials were carried out up to 1000 hr in the sulfuric acid environments of thermochemical hydrogen production IS process, focusing on the corrosion of welded portion and of crevice area. In the gas phase sulfuric acid decomposition condition at 850degC, welded samples of Alloy 800 and of Alloy 600 showed the same good corrosion resistance as the base materials. In the boiling condition of 95 wt% sulfuric acid solution, test sample of SiC showed the same good corrosion resistance. Also negligible corrosion was observed in crevice corrosion. (author)

  4. Wear resistance of laser-deposited boride reinforced Ti-Nb-Zr-Ta alloy composites for orthopedic implants

    International Nuclear Information System (INIS)

    Samuel, Sonia; Nag, Soumya; Scharf, Thomas W.; Banerjee, Rajarshi

    2008-01-01

    The inherently poor wear resistance of titanium alloys limits their application as femoral heads in femoral (hip) implants. Reinforcing the soft matrix of titanium alloys (including new generation β-Ti alloys) with hard ceramic precipitates such as borides offers the possibility of substantially enhancing the wear resistance of these composites. The present study discusses the microstructure and wear resistance of laser-deposited boride reinforced composites based on Ti-Nb-Zr-Ta alloys. These composites have been deposited using the LENS TM process from a blend of elemental Ti, Nb, Zr, Ta, and boron powders and consist of complex borides dispersed in a matrix of β-Ti. The wear resistance of these composites has been compared with that of Ti-6Al-4V ELI, the current material of choice for orthopedic femoral implants, against two types of counterfaces, hard Si 3 N 4 and softer SS440C stainless steel. Results suggest a substantial improvement in the wear resistance of the boride reinforced Ti-Nb-Zr-Ta alloys as compared with Ti-6Al-4V ELI against the softer counterface of SS440. The presence of an oxide layer on the surface of these alloys and composites also appears to have a substantial effect in terms of enhanced wear resistance

  5. Effect of heat treatment conditions on stress corrosion cracking resistance of alloy X-750 in high temperature water

    International Nuclear Information System (INIS)

    Yonezawa, Toshio; Onimura, Kichiro; Sakamoto, Naruo; Sasaguri, Nobuya; Susukida, Hiroshi; Nakata, Hidenori.

    1984-01-01

    In order to improve the resistance of the Alloy X-750 in high temperature and high purity water, the authors investigated the influence of heat treatment condition on the stress corrosion cracking resistance of the alloy. This paper describes results of the stress corrosion cracking test and some discussion on the mechanism of the stress corrosion cracking of Alloy X-750 in deaerated high temperature water. The following results were obtained. (1) The stress corrosion cracking resistance of Alloy X-750 in deaerated high temperature water remarkably depended upon the heat treatment condition. The materials solution heat treated and aged within temperature ranges from 1065 to 1100 0 C and from 704 to 732 0 C, respectively, have a good resistance to the stress corrosion cracking in deaerated high temperature water. Especially, water cooling after the solution heat treatment gives an excellent resistance to the stress corrosion cracking in deaerated high temperature water. (2) Any correlations were not observed between the stress corrosion cracking susceptibility of Alloy X-750 in deaerated high temperature water and grain boundary chromium depleted zones, precipitate free zones and the grain boundary segregation of impurity elements and so on. It appears that there are good correlations between the stress corrosion cracking resistance of the alloy in the environment and the kinds, morphology and coherency of precipitates along the grain boundaries. (author)

  6. Enhanced antibacterial properties, biocompatibility, and corrosion resistance of degradable Mg-Nd-Zn-Zr alloy.

    Science.gov (United States)

    Qin, Hui; Zhao, Yaochao; An, Zhiquan; Cheng, Mengqi; Wang, Qi; Cheng, Tao; Wang, Qiaojie; Wang, Jiaxing; Jiang, Yao; Zhang, Xianlong; Yuan, Guangyin

    2015-06-01

    Magnesium (Mg), a potential biodegradable material, has recently received increasing attention due to its unique antibacterial property. However, rapid corrosion in the physiological environment and potential toxicity limit clinical applications. In order to improve the corrosion resistance meanwhile not compromise the antibacterial activity, a novel Mg alloy, Mg-Nd-Zn-Zr (Hereafter, denoted as JDBM), is fabricated by alloying with neodymium (Nd), zinc (Zn), zirconium (Zr). pH value, Mg ion concentration, corrosion rate and electrochemical test show that the corrosion resistance of JDBM is enhanced. A systematic investigation of the in vitro and in vivo antibacterial capability of JDBM is performed. The results of microbiological counting, CLSM, SEM in vitro, and microbiological cultures, histopathology in vivo consistently show JDBM enhanced the antibacterial activity. In addition, the significantly improved cytocompatibility is observed from JDBM. The results suggest that JDBM effectively enhances the corrosion resistance, biocompatibility and antimicrobial properties of Mg by alloying with the proper amount of Zn, Zr and Nd. Copyright © 2015 Elsevier Ltd. All rights reserved.

  7. Characteristics of Resistance Spot Welded Ti6Al4V Titanium Alloy Sheets

    Directory of Open Access Journals (Sweden)

    Xinge Zhang

    2017-10-01

    Full Text Available Ti6Al4V titanium alloy is applied extensively in the aviation, aerospace, jet engine, and marine industries owing to its strength-to-weight ratio, excellent high-temperature properties and corrosion resistance. In order to extend the application range, investigations on welding characteristics of Ti6Al4V alloy using more welding methods are required. In the present study, Ti6Al4V alloy sheets were joined using resistance spot welding, and the weld nugget formation, mechanical properties (including tensile strength and hardness, and microstructure features of the resistance spot-welded joints were analyzed and evaluated. The visible indentations on the weld nugget surfaces caused by the electrode force and the surface expulsion were severe due to the high welding current. The weld nugget width at the sheets’ faying surface was mainly affected by the welding current and welding time, and the welded joint height at weld nugget center was chiefly associated with electrode force. The maximum tensile load of welded joint was up to 14.3 kN in the pullout failure mode. The hardness of the weld nugget was the highest because of the coarse acicular α′ structure, and the hardness of the heat-affected zone increased in comparison to the base metal due to the transformation of the β phase to some fine acicular α′ phase.

  8. Preparation of Phytic Acid/Silane Hybrid Coating on Magnesium Alloy and Its Corrosion Resistance in Simulated Body Fluid

    Science.gov (United States)

    Wang, Fengwu; Cai, Shu; Shen, Sibo; Yu, Nian; Zhang, Feiyang; Ling, Rui; Li, Yue; Xu, Guohua

    2017-09-01

    In order to decrease the corrosion rate and improve the bioactivity of magnesium alloy, phytic acid/saline hybrid coatings were synthesized on AZ31 magnesium alloys by sol-gel dip-coating method. It was found that the mole ratio of phytic acid to γ-APS had a great influence on coating morphology and the corresponding corrosion resistance of the coated magnesium alloys. When the mole ratio of phytic acid to γ-APS was 1:1, the obtained hybrid coating was integral and without cracks, which was ascribed to the strong chelate capability of phytic acid and Si-O-Si network derived from silane. Electrochemical test result indicated that the corrosion resistance of the coated magnesium alloy was about 27 times larger than that of the naked counterpart. In parallel, immersion test showed that the phytic acid/silane hybrid coating could induce CaP-mineralized product deposition, which offered another protection for magnesium alloy.

  9. The corrosion resistance of Zr-Nb and Zr-Nb-Sn alloys in high-temperature water and steam

    International Nuclear Information System (INIS)

    Dalgaard, S.B.

    1960-03-01

    An alloy of reactor-grade sponge zirconium-2.5 wt. % niobium was exposed to water and steam at high temperature. The corrosion was twice that of Zircaloy-2 while hydrogen pickup was found to be equal to that of Zircaloy-2. Ternary additions of tin to this alloy in the range 0.5-1.5 had no effect on the corrosion resistance in water at 315 o C up to 100 days. At higher temperatures, tin increased the corrosion, the effect varying with temperature. Heat treatment of the alloys was shown to affect corrosion resistance. (author)

  10. Avaliação da fundibilidade de uma liga de cobalto-cromo Castability evaluation of a cobalt-chromium alloy

    Directory of Open Access Journals (Sweden)

    Adriana da Fonte Porto CARREIRO

    1999-04-01

    Full Text Available Neste trabalho propusemo-nos a avaliar a fundibilidade de uma liga de cobalto-cromo (VERA-PDI em função da utilização de três revestimentos: Knebel (aglutinado por sílica, Termocast e Wirovest (aglutinados por fosfato e duas temperaturas de aquecimento para o molde (900°C e 950°C. Para a execução do teste foi utilizado o método descrito por HINMAN et al.9 (1985. O método de fundição foi o de cera perdida sob chama de gás-oxigênio. Os dados obtidos foram submetidos a análise estatística e demonstraram não haver diferença estatisticamente significante para os revestimentos Knebel e Wirovest, e diferença estatisticamente significante ao nível de 0,1% para o revestimento Termocast quando da variação da temperatura de aquecimento do molde. Quando analisamos os revestimentos sob temperatura do molde de 900°C verificamos diferença estatisticamente significante entre Knebel e Termocast e Knebel e Wirovest ao nível de 0,1%, e diferença entre Termocast e Wirovest ao nível de 5%. Para a temperatura de 950°C houve diferença estatisticamente significante ao nível de 0,1% entre todos os revestimentos. Dentro dos parâmetros utilizados neste estudo pudemos concluir que, para a liga VERA-PDI, a utilização do revestimento Knebel e temperatura de aquecimento do molde de 950°C proporcionaram melhores resultados quanto à fundibilidade.The purpose of this study was to evaluate the castability of a cobalt-chromium alloy (Vera-PDI using three investments: Knebel (agglutinated by silica, Termocast and Wirovest (both agglutinated by phosphate at two molding temperatures (900°C and 950°C; using HINMAN et al.9 (1985; methodology. The casting method of using a wax and gas-oxygen flame was used. There was no significant statistical difference between the Knebel and Wirovest investments; however, there was a statistically significant difference for Termocast investment (P < 0.1 at the different temperatures. When analyzing the

  11. Resistance Spot Welding of Aluminum Alloy to Steel with Transition Material - From Process to Performance

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xin; Stephens, Elizabeth V.; Khaleel, Mohammad A.; Shao, H; Kimchi, Menachem; Menachem Kimchi and Wanda Newman

    2004-05-11

    This paper summarizes work to date on resistance spot welding (RSW) of aluminum alloy to mild steel from process development to performance evaluation. A cold-rolled strip material is introduced as a transition material to aid the resistance welding process. The optimal welding parameters and electrode selections were established using a combination of experimental and analytical approaches. The mechanical behaviors of welded samples was evaluated using static and dynamic strength tests and cyclic fatigue tests. A statistical analysis was also performed to analyze the effect of different failure modes on the sample's peak load and energy absorption.

  12. Corrosion resistance of amorphous and crystalline Pd40Ni40P20 alloys in aqueous solutions

    DEFF Research Database (Denmark)

    Wu, Y.F.; Chiang, Wen-Chi; Chu, J.

    2006-01-01

    The corrosion behaviors of amorphous and crystalline Pd40Ni40P20 alloys in various aqueous solutions are reported in this paper. The corrosion resistance of crystalline (annealed) Pd40Ni40P20 is better than that of amorphous Pd40Ni40P20 in various corrosive solutions, due to crystalline Pd40Ni40P20...... and mainly consists of inert Pd5P2, NI3P, Ni2Pd2P and noble Pd phases. These inert and noble properties result in a higher corrosion resistance in crystalline Pd40Ni40P20....

  13. Correlation of microstructure and fatigue crack growth resistance in Ti-6Al-4V alloy

    CSIR Research Space (South Africa)

    Masete, Stephen

    2016-10-01

    Full Text Available of Microstructure and Fatigue Crack Growth Resistance in Ti-6Al-4V alloy Stephen Masete,1,2* Kalenda Mutombo1,2*, Roelf Mostert2, Charles Siyasiya2 and Waldo Stumpf2 1MSM/Light Metals, Council for Scientific and Industrial Research, (CSIR), Pretoria..., South Africa 2Department of Materials Science and Metallurgical Engineering, University of Pretoria, Pretoria, South Africa *Email: smasete@csir.co.za, kmutombo@csir.co.za The effect of the microstructure on fatigue crack growth resistance...

  14. Understanding effects of microstructural inhomogeneity on creep response – New approaches to improve the creep resistance in magnesium alloys

    Directory of Open Access Journals (Sweden)

    Yuanding Huang

    2014-06-01

    Full Text Available Previous investigations indicate that the creep resistance of magnesium alloys is proportional to the stability of precipitated intermetallic phases at grain boundaries. These stable intermetallic phases were considered to be effective to suppress the deformation by grain boundary sliding, leading to the improvement of creep properties. Based on this point, adding the alloying elements to form the stable intermetallics with high melting point became a popular way to develop the new creep resistant magnesium alloys. The present investigation, however, shows that the creep properties of binary Mg–Sn alloy are still poor even though the addition of Sn possibly results in the precipitation of thermal stable Mg2Sn at grain boundaries. That means other possible mechanisms function to affect the creep response. It is finally found that the poor creep resistance is attributed to the segregation of Sn at dendritic and grain boundaries. Based on this observation, new approaches to improve the creep resistance are suggested for magnesium alloys because most currently magnesium alloys have the commonality with the Mg–Sn alloys.

  15. A new high-strength iron base austenitic alloy with good toughness and corrosion resistance (GE-EPRI alloy-TTL)

    International Nuclear Information System (INIS)

    Ganesh, S.

    1989-01-01

    A new high strength, iron based, austenitic alloy has been successfully developed by GE-EPRI to satisfy the strength and corrosion resistance requirements of large retaining rings for high capacity generators (>840Mw). This new alloy is a modified version of the EPRI alloy-T developed by the University of California, Berkeley, in an earlier EPRI program. It is age hardenable and has the nominal composition (weight %): 34.5 Ni, 5Cr, 3Ti, 1Nb, 1Ta, 1Mo, .5Al, .3V, .01B. This composition was selected based on detailed metallurgical and processing studies on modified versions of alloy-T. These studies helped establish the optimum processing conditions for the new alloy and enabled the successful scale-up production of three large (50-52 inch dia) test rings from a 5,000 lb VIM-VAR billet. The rings were metallurgically sound and exhibited yield strength capabilities in the range 145 to 220 ksi depending on the extent of hot/cold work induced. The test rings met or exceeded all the property goals. The above alloy can provide a good combination of strength, toughness and corrosion resistance and, through an suitable modification of chemistry or processing conditions, could be a viable candidate for high strength LWR internal applications. 3 figs

  16. Compatibility of heat resistant alloys with boron carbide, (2)

    International Nuclear Information System (INIS)

    Baba, Shin-ichi; Nagamatuya, Takaaki; Aoyama, Isao; Ito, Hisanori; Muraoka, Susumu.

    1982-12-01

    In the present design of the control rod for the experimental Very High Temperature Gas-cooled Reactor, sintered pellets of boron carbide mixed with graphite are used as a neutron absorber, which are clad with the sheath material of Hastelloy XR. The sintered pellet contains 30 wt% of natural boron. Chemical reaction occurs between the neutron absorber and the sheath material when they contact mutually at elevated temperature. The term called compatibility is defined as the ability of those materials to be used together without undesirable reaction, in this report. The experimental results on the compatibility of both materials are presented and are discussed on three subjects as (1) the comparison between Hastelloy X and Hastelloy XR, (2) the long term exposure, (3) the effect of the reaction barrier. No difference was observed between Hastelloy X and Hastelloy XR within the conditions of the experiment at 850 0 C, 950 0 C and 1050 0 C for each 100 h concerning the first subject. On the second, the penetration depth of 74 um and 156 um were observed on Hastelloy X reacted with sintered pellets (boron carbide and graphite) at 750 0 C for 3000 h and 850 0 C for 2000 h, respectively. On the third subject, Hastelloy X surfaces were coated with zirconia or alumina powder by plasma spraying process and by calorizing process in order to prevent the above mentioned reaction. These specimens were tested under two conditions: the one was a simple heat test of 1000 0 C - 100 h and the other was five thermal cycles of 1000 0 C - 20 h. The test results showed that no reaction occurred in the both alloys themselves and some of the coated layers were stripped or cracked. (author)

  17. Martensitic/ferritic super heat-resistant 650 C steels - design of model alloys

    Energy Technology Data Exchange (ETDEWEB)

    Knezevic, V.; Sauthoff, G. [Max-Planck-Inst. fuer Eisenforschung GmbH, Duesseldorf (Germany)

    2002-07-01

    Tempered martensitic/ferritic 9-12%Cr steels are now recognized to be the most potential materials for 650 C ultra super critical (USC) Power Plants. The degradation of long-term creep strength, as a result of microstructural changes during long-term exposure at the elevated temperature, is the main problem for this group of steels. Therefore, to achieve sufficient creep resistance during the entire service life it is necessary to stabilize the microstructure by alloying with elements which provide enough solid solution and precipitation strengthening and slow down diffusion. The aim of the present study is to investigate the effect of different types of precipitates as well as alloying elements on mechanical long-term properties of new ferritic 12%Cr steels. Fine distributions of stable precipitates which block the movement of subgrain boundaries (M{sub 23}C{sub 6} carbides, Laves phase) and dislocations (MX carbonitrides) and delay coarsening of microstructure is the key to high creep strength of such steels. Furthermore, additional Laves phase, which precipitates during service, is to strengthen the alloys when M{sub 23}C{sub 6} particles become less effective. Addition of Co is to achieve an initially 100% martensitic microstructure and moreover to slow down diffusion processes and consequently coarsening of particles. The partial substitution of Co by Cu and Mn is also investigated to reduce costs. The first results of mechanical tests of the studied model alloys have shown positive effects of the addition of W as Laves phase forming element, as well as of the MX forming elements Ta and Ti. Alloying with Co has also shown beneficial effects on the creep strength of model alloys. Further optimisation of composition and microstructure is in progress. (orig.)

  18. Influence of supply of heat to cobalt-chromium frameworks during soldering and subsequent hardening heat treatment of wrought clasps.

    Science.gov (United States)

    Eriksson, T; Sjögren, G; Bergman, M

    1983-01-01

    Retentive clasp arms of wrought gold alloy wire were soldered to frameworks made of three dental cobalt-chromium alloys. The clasps were then subjected to a conventional hardening heat treatment. Microstructure and hardness of the cobalt-chromium alloys were determined before and after these operations. The results reveal that the supply of heat during soldering and hardening heat treatment of the clasp does not influence the microstructure and hardness of the cobalt-chromium alloys.

  19. Effect of composition on corrosion resistance of high-alloy austenitic stainless steel weld metals

    International Nuclear Information System (INIS)

    Marshall, P.I.; Gooch, T.G.

    1993-01-01

    The corrosion resistance of stainless steel weld metal in the ranges of 17 to 28% chromium (Cr), 6 to 60% nickel (Ni), 0 to 9% molybdenum (Mo), and 0.0 to 0.37% nitrogen (N) was examined. Critical pitting temperatures were determined in ferric chloride (FeCl 3 ). Passive film breakdown potentials were assessed from potentiodynamic scans in 3% sodium chloride (NaCl) at 50 C. Potentiodynamic and potentiostatic tests were carried out in 30% sulfuric acid (H 2 SO 4 ) ar 25 C, which was representative of chloride-free acid media of low redox potential. Metallographic examination and microanalysis were conducted on the test welds. Because of segregation of alloying elements, weld metal pitting resistance always was lower than that of matching composition base steel. The difference increased with higher Cr, Mo, and N contents. Segregation also reduced resistance to general corrosion in H 2 SO 4 , but the effect relative to the base steel was less marked than with chloride pitting. Segregation of Cr, Mo, and N in fully austenitic deposits decreased as the Ni' eq- Cr' eq ratio increased. Over the compositional range studied, weld metal pitting resistance was dependent mainly on Mo content and segregation. N had less effect than in wrought alloys. Both Mo and N enhanced weld metal corrosion resistance in H 2 SO 4

  20. Resistivity behavior in isothermal annealing of Pd-H(D) alloys around 50 K

    International Nuclear Information System (INIS)

    Yamakawa, Kohji; Maeta, Hiroshi

    2004-01-01

    The behavior of electrical resistivity during hydrogen (deuterium) ordering is investigated for Pd-H(D) alloys of various hydrogen concentrations around 50 K. The disordered hydrogen (deuterium) atoms are introduced by quenching from 100 K into liquid helium immediately before isothermal annealings. The disordered atoms order by migration of the atoms during the heating-up of the specimens. On the isothermal curves of the resistivity in the high temperature range, the resistivity increases at first and then adopts a constant value dependent on the annealing temperature. On the other hand, the resistivity increases and then decreases during isothermal annealing in the low temperature range, nevertheless the ordering is progressing. The annealing time, at which the resistivity maximum appears, and the resistivity value of the maximum increase with decreasing annealing temperature. Furthermore, the decreasing resistivity after the maximum saturates to a value dependent on each annealing temperature. Therefore, it becomes clear that an equilibrium amount of ordering depends on the temperature and the resistivity increases in the early stage of hydrogen (deuterium) ordering and decreases in the later stage. The resistivity maximum in the isothermal annealing curve is caused by the nucleation and growth of ordered domains of hydrogen (deuterium) atoms

  1. The cytotoxicity and genotoxicity of soluble and particulate cobalt in human lung fibroblast cells

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Leah J.; Holmes, Amie L. [Wise Laboratory of Environmental and Genetic Toxicology, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Maine Center for Environmental Toxicology and Health, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Department of Applied Medical Science, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Kandpal, Sanjeev Kumar; Mason, Michael D. [Department of Chemical and Biological Engineering, University of Maine, Orono, ME (United States); Zheng, Tongzhang [Department of Environmental Health Sciences, Yale School of Public Health, New Haven, CT (United States); Wise, John Pierce, E-mail: John.Wise@usm.maine.edu [Wise Laboratory of Environmental and Genetic Toxicology, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Maine Center for Environmental Toxicology and Health, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States); Department of Applied Medical Science, University of Southern Maine, 96 Falmouth St., P.O. Box 9300, Portland, ME 04101-9300 (United States)

    2014-08-01

    Cobalt exposure is increasing as cobalt demand rises worldwide due to its use in enhancing rechargeable battery efficiency, super-alloys, and magnetic products. Cobalt is considered a possible human carcinogen with the lung being a primary target. However, few studies have considered cobalt-induced toxicity in human lung cells. Therefore, in this study, we sought to determine the cytotoxicity and genotoxicity of particulate and soluble cobalt in human lung cells. Cobalt oxide and cobalt chloride were used as representative particulate and soluble cobalt compounds, respectively. Exposure to both particulate and soluble cobalt induced a concentration-dependent increase in cytotoxicity, genotoxicity, and intracellular cobalt ion levels. Based on intracellular cobalt ion levels, we found that soluble cobalt was more cytotoxic than particulate cobalt while particulate and soluble cobalt induced similar levels of genotoxicity. However, soluble cobalt induced cell cycle arrest indicated by the lack of metaphases at much lower intracellular cobalt concentrations compared to cobalt oxide. Accordingly, we investigated the role of particle internalization in cobalt oxide-induced toxicity and found that particle-cell contact was necessary to induce cytotoxicity and genotoxicity after cobalt exposure. These data indicate that cobalt compounds are cytotoxic and genotoxic to human lung fibroblasts, and solubility plays a key role in cobalt-induced lung toxicity. - Highlights: • Particulate and soluble cobalt are cytotoxic and genotoxic to human lung cells. • Soluble cobalt induces more cytotoxicity compared to particulate cobalt. • Soluble and particulate cobalt induce similar levels of genotoxicity. • Particle-cell contact is required for particulate cobalt-induced toxicity.

  2. Corrosion resistance and microstructure of alloy 625 weld overlay on ASTM A516 grade 70

    Energy Technology Data Exchange (ETDEWEB)

    Moradi, Mohammad J. [Amirkabir Univ. of Technology, Tehran (Iran, Islamic Republic of). Petroleum Engineering Dept.; Ketabchi, Mostafa [Amirkabir Univ. of Technology, Tehran (Iran, Islamic Republic of). Mining and Metallurgical Engineering Dept.

    2016-02-01

    Nickel-based alloys are a crucial class of materials because of their excellent corrosion resistance. In the present study, single layer and two layers alloy 625 weld overlays were deposited by GTAW process on A516 grade 70 carbon steel. The dilution in terms of Fe, Ni, Mo and Nb content was calculated in 30 points of weld overlay. Microstructure observations showed that alloy 625 had austenitic structure with two types of Laves and NbC secondary phases. The uniform and pitting corrosion resistance of alloy 625 weld overlay as casted and as forged were evaluated in accordance with ASTM G48-2011 standard at different temperatures to determine the weight loss and critical pitting temperature. For achieving a better comparison, samples from alloy 625 as casted and as forged were tested under the same conditions. The results point out that single layer alloy 625 weld overlay is not suitable for chloride containing environments, two layers alloy 625 weld overlay and alloy 625 as casted have acceptable corrosion resistance and almost the same critical pitting temperature. Alloy 625 as forged has the best corrosion resistance and the highest critical pitting temperature among all test specimens. Also, the corrosion behavior was evaluated in accordance with ASTM G28 standard. The corrosion rate of single layer weld overlay was unacceptable. The average corrosion rate of two layers weld overlay and in casted condition were 35.82 and 33.01 mpy, respectively. [German] Nickellegierungen sind aufgrund ihres exzellenten Korrosionswiderstandes eine bedeutende Werkstoffklasse. In der diesem Beitrag zugrunde liegenden Studie wurden mittels WIG-Schweissens ein- und zweilagige Schweissplattierungen auf den Kohlenstoffstahl A516 (Grade 70) aufgebracht. Die Vermischung in Form des Fe-, Ni-, Mo- und Nb-Gehaltes wurde an 30 Punkten der Schweissplattierungen berechnet. Die mikrostrukturellen Untersuchungen ergaben, dass die Legierung 625 eine austenitische Struktur mit zwei Arten von

  3. Microstructures, mechanical properties and corrosion resistances of extruded Mg-Zn-Ca-xCe/La alloys.

    Science.gov (United States)

    Tong, L B; Zhang, Q X; Jiang, Z H; Zhang, J B; Meng, J; Cheng, L R; Zhang, H J

    2016-09-01

    Magnesium alloys are considered as good candidates for biomedical applications, the influence of Ce/La microalloying on the microstructure, mechanical property and corrosion performance of extruded Mg-5.3Zn-0.6Ca (wt%) alloy has been investigated in the current study. After Ce/La addition, the conventional Ca2Mg6Zn3 phases are gradually replaced by new Mg-Zn-Ce/La-(Ca) phases (T1'), which can effectively divide the Ca2Mg6Zn3 phase. The Ca2Mg6Zn3/T1' structure in Mg-Zn-Ca-0.5Ce/La alloy is favorably broken into small particles during the extrusion, resulting in an obvious refinement of secondary phase. The dynamic recrystallized grain size is dramatically decreased after 0.5Ce/La addition, and the tensile yield strength is improved, while further addition reverses the effect, due to the grain coarsening. However, the corrosion resistance of extruded Mg-Zn-Ca alloy deteriorates after Ce/La addition, because the diameter of secondary phase particle is remarkably decreased, which increases the amount of cathodic sites and accelerates the galvanic corrosion process. Copyright © 2016 Elsevier Ltd. All rights reserved.

  4. Rapid fabrication of large-area, corrosion-resistant superhydrophobic Mg alloy surfaces.

    Science.gov (United States)

    Xu, Wenji; Song, Jinlong; Sun, Jing; Lu, Yao; Yu, Ziyuan

    2011-11-01

    A superhydrophobic magnesium (Mg) alloy surface was successfully fabricated via a facile electrochemical machining process, and subsequently covered with a fluoroalkylsilane (FAS) film. The surface morphologies and chemical compositions were investigated using a scanning electron microscope (SEM) equipped with an energy-dispersive spectroscopy (EDS) and a Fourier-transform infrared spectrophotometer (FTIR). The results show hierarchal rough structures and an FAS film with a low surface energy on the Mg alloy surfaces, which confers good superhydrophobicity with a water contact angle of 165.2° and a water tilting angle of approximately 2°. The processing conditions, such as the processing time and removal rate per unit area at a constant removal mass per unit area, were investigated to determine their effects on the superhydrophobicity. Interestingly, when the removal mass per unit area is constant at approximately 11.10 mg/cm(2), the superhydrophobicity does not change with the removal rate per unit area. Therefore, a superhydrophobic Mg alloy surface can be rapidly fabricated based on this property. A large-area superhydrophobic Mg alloy surface was also fabricated for the first time using a small-area moving cathode. The corrosion resistance and durability of the superhydrophobic surfaces were also examined.

  5. Enhancement of viability of radiosensitive (PBMC) and resistant (MDA-MB-231) clones in low-dose-rate cobalt-60 radiation therapy

    Energy Technology Data Exchange (ETDEWEB)

    Falcao, Patricia Lima, E-mail: patricialfalcao@gmail.com [Universidade Federal do Amazonas (UFAM), Manaus, AM (Brazil); Motta, Barbara Miranda; Lima, Fernanda Castro de; Lima, Celso Vieira; Campos, Tarcisio Passos Ribeiro [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil)

    2015-05-15

    Objective: in the present study, the authors investigated the in vitro behavior of radio-resistant breast adenocarcinoma (MDA-MB-231) cells line and radiosensitive peripheral blood mononuclear cells (PBMC), as a function of different radiation doses, dose rates and postirradiation time kinetics, with a view to the interest of clinical radiotherapy. Materials and methods: the cells were irradiated with Co-60, at 2 and 10 Gy and two different exposure rates, 339.56 cGy.min{sup -1} and the other corresponding to one fourth of the standard dose rates, present over a 10-year period of cobalt therapy. Post-irradiation sampling was performed at pre-established kinetics of 24, 48 and 72 hours. The optical density response in viability assay was evaluated and a morphological analysis was performed. Results: radiosensitive PBMC showed decrease in viability at 2 Gy, and a more significant decrease at 10 Gy for both dose rates. MDAMB-231 cells presented viability decrease only at higher dose and dose rate. The results showed MDA-MB-231 clone expansion at low dose rate after 48-72 hours post-radiation. Conclusion: low dose rate shows a possible potential clinical impact involving decrease in management of radio-resistant and radiosensitive tumor cell lines in cobalt therapy for breast cancer. (author)

  6. Enhancement of viability of radiosensitive (PBMC and resistant (MDA-MB-231 clones in low-dose-rate cobalt-60 radiation therapy

    Directory of Open Access Journals (Sweden)

    Patrícia Lima Falcão

    2015-06-01

    Full Text Available Abstract Objective: In the present study, the authors investigated the in vitro behavior of radio-resistant breast adenocarcinoma (MDA-MB-231 cells line and radiosensitive peripheral blood mononuclear cells (PBMC, as a function of different radiation doses, dose rates and postirradiation time kinetics, with a view to the interest of clinical radiotherapy. Materials and Methods: The cells were irradiated with Co-60, at 2 and 10 Gy and two different exposure rates, 339.56 cGy.min–1 and the other corresponding to one fourth of the standard dose rates, present over a 10-year period of cobalt therapy. Post-irradiation sampling was performed at pre-established kinetics of 24, 48 and 72 hours. The optical density response in viability assay was evaluated and a morphological analysis was performed. Results: Radiosensitive PBMC showed decrease in viability at 2 Gy, and a more significant decrease at 10 Gy for both dose rates. MDAMB- 231 cells presented viability decrease only at higher dose and dose rate. The results showed MDA-MB-231 clone expansion at low dose rate after 48–72 hours post-radiation. Conclusion: Low dose rate shows a possible potential clinical impact involving decrease in management of radio-resistant and radiosensitive tumor cell lines in cobalt therapy for breast cancer.

  7. Informatics Aided Design for Alloys

    Science.gov (United States)

    2009-02-28

    alloying discoveries/ predictions of new ternary cobalt based alloys that can have improved properties from conventional nickel based superalloys ...Using this approach we have proposed new ternary alloy additions for binary cobalt based intermetallics. Through comparison with some recent...that are even better than nickel base superalloys . This strategy has also been extended to the development of new type of design maps that identify

  8. Effects of composite scale on high temperature oxidation resistance of Fe-Cr-Ni heat resistant alloy

    Directory of Open Access Journals (Sweden)

    Wang Haitao

    2009-05-01

    Full Text Available Fe-Cr-Ni heat resistant alloys with aluminum and silicon addition, alone and in combination, were melted using an intermediate frequency induction furnace with a non-oxidation method. By the oxidation weight gain method, the oxidation resistances of the test alloys were determined at 1,200 ìC for 500 hours. According to the oxidation weight gains, the oxidation kinetic curves were plotted and the functions were regressed by the least squares method. The results show that the oxidation kinetic curves follow the power function of y = axb (a>0, 0resistance were studied further by analyses using X-ray diffraction (XRD and scanning electron microscope (SEM. It is found that the composite scale compounds of Cr2O3, メ-Al2O3, SiO2 and FeCr2O4, with compact structure and tiny grains, shows complete oxidation resistance at 1,200 ìC. When the composite scale lacks メ-Al2O3 or SiO2, it becomes weak in oxidation resistance with a loose structure. By the criterion of standard Gibbs formation free energy, the model of the nucleation and growth of the composite scale is established. The forming of the composite scale is the result of the competition of being oxidized and reduced between aluminum, silicon and the matrix metal elements of iron, chromium and nickel. The protection of the composite scale is analyzed essentially by electrical conductivity and strength properties.

  9. Invar and Elinvar type amorphous Fe-Cr-B alloys with high corrosion resistance

    Science.gov (United States)

    Kikuci, M.; Fukamichi, K.; Masumoto, T.

    1987-01-01

    Amorphous (Fe(1-x)Cr(x))85B15 alloys (x = 0 to 0.15) were prepared from the melts by rapid quenching using a single roller techinque, and their Invar and Elinvar characteristics and corrosion resistance were investigated. With an increase in chromium content the Curie temperature and the saturation magnetic moment per iron atom decreased monotonically, while the crystallization temperature incresed gradually. The thermal expansion coefficient alpha around room temperature became slightly larger with increasing chromium content. Nevertheless, these amorphous alloys exhibited excellent Invar characteristics below the Curie temperature. The value of Young's modulus increased remarkably in a relatively low magnetic field and then saturated at a field of about 80 kA/m, showing a large delta E effect. Its value as well as a longitudinal linear magnetostriction became smaller with an increase in chromium content. The temperature coefficient of Young's modulus changed from postive to negative, and the temperature range showing the Elinvar characteristics became narrower with chromium content. The temperature coefficient of delay time determined from the values of alpha and e was very small. The corrosion resistance of these alloys was extremely improved by chromium addition.

  10. Fabrication of biomimetic hydrophobic films with corrosion resistance on magnesium alloy by immersion process

    International Nuclear Information System (INIS)

    Liu Yan; Lu Guolong; Liu Jindan; Han Zhiwu; Liu Zhenning

    2013-01-01

    Highlights: ► We have developed a facile and simple method of creating a hydrophobic surface on a magnesium alloy by an immersion process at room temperature. ► The distribution of the micro-structure and the roughness of the surface play critical roles in transforming from hydrophilic to hydrophobic. ► The hydrophobic coatings possess better corrosion resistance than magnesium alloy matrix. - Abstract: Biomimetic hydrophobic films of crystalline CeO 2 were prepared on magnesium alloy by an immersion process with cerium nitrate solution and then modified with DTS (CH 3 (CH 2 ) 11 Si(OCH 3 ) 3 ). The CeO 2 films fabricated with 20-min immersion yield a water contact angle of 137.5 ± 2°, while 20-min DTS treatment on top of CeO 2 can further enhance the water contact angle to 146.7 ± 2°. Then corrosion-resistant property of these prepared films against NaCl solution was investigated and elucidated using electrochemical measurements.

  11. Influence of Processing and Heat Treatment on Corrosion Resistance and Properties of High Alloyed Steel Coatings

    Science.gov (United States)

    Hill, Horst; Weber, Sebastian; Raab, Ulrich; Theisen, Werner; Wagner, Lothar

    2012-09-01

    Corrosion and abrasive wear are two important aspects to be considered in numerous engineering applications. Looking at steels, high-chromium high-carbon tool steels are proper and cost-efficient materials. They can either be put into service as bulk materials or used as comparatively thin coatings to protect lower alloyed construction or heat treatable steels from wear and corrosion. In this study, two different corrosion resistant tool steels were used for the production of coatings and bulk material. They were processed by thermal spraying and super solidus liquid phase sintering as both processes can generally be applied to produce coatings on low alloyed substrates. Thermally sprayed (high velocity oxygen fuel) coatings were investigated in the as-processed state, which is the most commonly used condition for technical applications, and after a quenching and tempering treatment. In comparison, sintered steels were analyzed in the quenched and tempered condition only. Significant influence of alloy chemistry, processing route, and heat treatment on tribological properties was found. Experimental investigations were supported by computational thermodynamics aiming at an improvement of tribological and corrosive resistance.

  12. Effect of thermal aging on corrosion resistance of C-22 alloy in chloride solutions

    International Nuclear Information System (INIS)

    Carranza, Ricardo M.; Rodriguez, Martin A.

    2007-01-01

    Alloy 22 (N06022) belongs to the Ni-Cr-Mo family and it is highly resistant to localized corrosion. The anodic behavior of mill annealed (MA) and thermally aged (10 hours at 760 C degrees) Alloy 22 was studied in chloride solutions with different pH values at 90 C degrees. Thermal aging leads to a microstructure of full grain boundary precipitation of topologically closed packed (TCP) phases. Electrochemical tests included monitoring of open circuit potential, potentiodynamic polarization and electrochemical impedance spectroscopy. Assessment of general and localized (crevice) corrosion was performed. Re passivation potentials were obtained from cyclic potentiodynamic polarization tests. Results indicate that MA and TCP material show similar general corrosion rates and crevice corrosion resistance in the tested environments. MA and TCP specimens suffered general corrosion in an active state when tested in low pH chloride solutions. The grain structure of the alloy was revealed for MA material, while TCP material suffered a preferential attack at grain boundaries. (author)

  13. Corrosion Behavior of New Cr-Ni-Cu Low Alloy Seawater Corrosion Resistant Steel

    Science.gov (United States)

    Zhang, Piaopiao; Yang, Zhongmin; Chen, Ying; Wang, Huimin

    Two kinds of Cr-Ni-Cu low alloyed steels were designed, 0.1%C-0.7%Cr-1.2%Ni-0.7Cu and 0.1%C-0.7%Cr-0.3%Ni-0.5Cu. With the method of SEM, XRD and electrochemical analysis and testing technology, periodic immersion accelerated corrosion test was carried out to investigate the corrosion resistance of the designed steels in simulated marine environment. The steel with best corrosion resistance was selected, and then focused on the variation of its corrosion rate with time. The results indicated that the designed Cu-Cr-Ni low alloyed steels showed better corrosion resistance than 20MnSi, the ratio of their corrosion rates was 0.44. The corrosion rate of designed steels decreased gradually to 3 4 g/(mm2·h) with the elongation of test period, while the corrosion rate of 20MnSi kept downward trend, not reach stability, and the corrosion rate gap between them became smaller. The Cr element banding enriched in the inner rust can withstand the diffusion of Cl-. Besides, the addition of Ni raised the self-corrosion potential of the bare steels and promoted the transformation of γ-FeOOH to α-FeOOH, and consequently, improved the stability of the rust and the corrosion resistance of steels.

  14. Mechanical and tribological properties of newly developed Tribaloy alloys

    International Nuclear Information System (INIS)

    Xu, W.; Liu, R.; Patnaik, P.C.; Yao, M.X.; Wu, X.J.

    2007-01-01

    Outstanding combination of mechanical, wear and corrosion performance has been achieved in Laves intermetallic materials, termed Tribaloy alloys. In these two-phase alloys the solid solution provides high mechanical strength and fracture toughness while the Laves intermetallic phase offers excellent wear resistance. However, conventional Tribaloy alloys usually have low tensile strength and fracture toughness compared with ductile materials due to the large volume fraction of Laves phase, which has limited their application in many cases. The present research is aimed at developing advanced Tribaloy alloys with increasing ductility. Two new cobalt base alloys were developed in this research. The specimens were fabricated with a centrifugal casting technique. The material characterization was performed using the differential scanning calorimetry (DSC), scanning electron microscope (SEM), indentation and ball-on-disc tribological techniques

  15. Enhancement of wear and ballistic resistance of armour grade AA7075 aluminium alloy using friction stir processing

    Directory of Open Access Journals (Sweden)

    I. Sudhakar

    2015-03-01

    Full Text Available Industrial applications of aluminium and its alloys are restricted because of their poor tribological properties. Thermal spraying, laser surfacing, electron beam welding are the most widely used techniques to alter the surface morphology of base metal. Preliminary studies reveal that the coating and layering of aluminium alloys with ceramic particles enhance the ballistic resistance. Furthermore, among aluminium alloys, 7075 aluminium alloy exhibits high strength which can be compared to that of steels and has profound applications in the designing of lightweight fortification structures and integrated protection systems. Having limitations such as poor bond integrity, formation of detrimental phases and interfacial reaction between reinforcement and substrate using fusion route to deposit hard particles paves the way to adopt friction stir processing for fabricating surface composites using different sizes of boron carbide particles as reinforcement on armour grade 7075 aluminium alloy as matrix in the present investigation. Wear and ballistic tests were carried out to assess the performance of friction stir processed AA7075 alloy. Significant improvement in wear resistance of friction stir processed surface composites is attributed to the change in wear mechanism from abrasion to adhesion. It has also been observed that the surface metal matrix composites have shown better ballistic resistance compared to the substrate AA7075 alloy. Addition of solid lubricant MoS2 has reduced the depth of penetration of the projectile to half that of base metal AA7075 alloy. For the first time, the friction stir processing technique was successfully used to improve the wear and ballistic resistances of armour grade high strength AA7075 alloy.

  16. Influence of Tensile Stresses on α+β – Titanium Alloy VT22 Corrosion Resistance in Marine Environment

    Directory of Open Access Journals (Sweden)

    Yu. A. Puchkov

    2015-01-01

    Full Text Available Tensile stresses and hydrogen render strong influence on the titanic alloys propensity for delayed fracture. The protective film serves аs a barrier for penetration in hydrogen alloy. Therefore to study the stress effect on its structure and protective properties is of significant interest.The aim of this work is to research the tensile stress influence on the passivation, indexes of corrosion, protective film structure and reveal reasons for promoting hydrogenation and emerging propensity for delayed fracture of titanium alloy VТ22 in the marine air atmosphere.The fulfillеd research has shown that:- there is а tendency to reduce the passivation abilities of the alloy VТ22 in synthetic marine water (3 % solution of NaCl with increasing tensile stresses up to 1170 МPа, namely to reduce the potential of free corrosion and the rate of its сhange, thus the alloy remains absolutely (rather resistant;- the protective film consists of a titanium hydroxide layer under which there is the titanium oxide layer adjoining to the alloy, basically providing the corrosion protection.- the factors providing hydrogenation of titanium alloys and formation in their surface zone fragile hydrides, causing the appearing propensity for delayed fracture, alongside with tensile stresses are:- substances promoting chemisorbtion of hydrogen available in the alloy and on its surface;- the cathodic polarization caused by the coupling;- the presence of the structural defects promoting the formation of pitting and local аcidifying of the environment surrounding the alloy.

  17. Control and optimization of baths for electrodeposition of Co-Mo-B amorphous alloys

    Directory of Open Access Journals (Sweden)

    S. Prasad

    2000-12-01

    Full Text Available Optimization and control of an electrodeposition process for depositing boron-containing amorphous metallic layer of cobalt-molybdenum alloy onto a cathode from an electrolytic bath having cobalt sulfate, sodium molybdate, boron phosphate, sodium citrate, 1-dodecylsulfate-Na, ammonium sulfate and ammonia or sulfuric acid for pH adjustments has been studied. Detailed studies on bath composition, pH, temperature, mechanical agitation and cathode current density have led to optimum conditions for obtaining satisfactory alloy deposits. These alloys were found to have interesting properties such as high hardness, corrosion resistance, wear resistance and also sufficient ductility. A voltammetric method for automatic monitoring and control of the process has been proposed.

  18. Effects of soluble cobalt and cobalt incorporated into calcium phosphate layers on osteoclast differentiation and activation

    NARCIS (Netherlands)

    Patntirapong, Somying; Habibovic, Pamela; Hauschka, Peter V.

    2009-01-01

    Metal ions originating from mechanical debris and corrosive wear of prosthetic implant alloys accumulate in peri-implant soft tissues, bone mineral, and body fluids. Eventually, metal ions such as cobalt (II) (Co2+), which is a major component of cobalt–chromium-based implant alloys and a known

  19. Numerical description of creep of highly creep resistant alloys

    International Nuclear Information System (INIS)

    Preussler, T.

    1991-01-01

    Fatigue tests have been performed with a series of highly creep resistant materials for gas turbines and related applications for gaining better creep data up to long-term behaviour. The investigations were performed with selected individual materials in the area of the main applications down to strains and stresses relevant to design, and have attained trial durations of 25000 to 60000 h. In continuing former research, creep equations for a selection of characterizing individual materials have been improved and partly newly developed on the basis of a differentiated evaluation. Concerning the single materials, there are: one melt each of the materials IN-738 LC, IN-939, IN-100, FSX-414 and Inconel 617. The applied differentiated evaluation is based on the elastoplastical behaviour from the hot-drawing test, the creep behaviour from the non interrupted or the interrupted fatigue test, and the contraction behaviour from the annealing test. The creep equations developed describe the high temperature deformation behaviour taking into account primary, secondary and partly the tertiary creep dependent of temperature, stress and time. These equations are valid for the whole application area of the respective material. (orig./MM) [de

  20. Precipitation hardenable iron-nickel-chromium alloy having good swelling resistance and low neutron absorbence

    International Nuclear Information System (INIS)

    Korenko, M.K.; Merrick, H.F.; Gibson, R.C.

    1982-01-01

    An iron-nickel-chromium age-hardenable alloy suitable for use in fast breeder reactor ducts and cladding utilizes the gamma-double prime strengthening phase and has a morphology of the gamma-double prime phase enveloping the gamma-prime phase and delta phase distributed at or near the grain boundaries. The alloy consists essentially of about 40-50 percent nickel, 7.5-14 percent chromium, 1.5-4 percent niobium, .25-.75 percent silicon, 1-3 percent titanium, .1-.5 percent aluminum, .02-1 percent carbon, .002-.015 percent boron, and the balance iron. Up to 2 percent manganese and up to .01 percent magnesium may be added to inhibit trace element effects; up to .1 percent zirconium may be added to increase radiation swelling resistance; and up to 3 percent molybdenum may be added to increase strength

  1. Oxidation Behavior and Chlorination Treatment to Improve Oxidation Resistance of Nb-Mo-Si-B Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Behrani, Vikas [Iowa State Univ., Ames, IA (United States)

    2004-01-01

    This thesis is written in an alternate format. The thesis is composed of a general introduction, two original manuscripts, and a general conclusion. References cited within each chapter are given at the end of each chapter. The general introduction starts with the driving force behind this research, and gives an overview of previous work on boron doped molybdenum silicides, Nb/Nb5Si3 composites, boron modified niobium silicides and molybdenum niobium silicides. Chapter 2 focuses on the oxidation behavior of Nb-Mo-Si-B alloys. Chapter 3 contains studies on a novel chlorination technique to improve the oxidation resistance of Nb-Mo-Si-B alloys. Chapter 4 summarizes the important results in this study.

  2. Study on Composition, Microstructure and Wear Behavior of Fe-B-C Wear-Resistant Surfacing Alloys

    Science.gov (United States)

    Zhuang, Minghui; Li, Muqin; Wang, Jun; Ma, Zhen; Yuan, Shidan

    2017-12-01

    Fe-B-C alloy layers with various microstructures were welded on Q235 steel plates using welding powders/H08Mn2Si and welding wires composite surfacing technology. The relationship existing between the chemical composition, microstructure and wear resistance of the surfacing alloy layers was investigated by scanning electron microscopy, x-ray diffraction, electron backscatter diffraction and wear tests. The results demonstrated that the volume fractions and morphologies of the microstructures in the surfacing alloy layers could be controlled by adjusting the boron and carbon contents in the welding powders, which could further regulate the wear resistance of the surfacing alloy layers. The typical microstructures of the Fe-B-C surfacing alloy layers included dendritic Fe, rod-like Fe2B, fishbone-like Fe2B and daisy-like Fe3(C, B). The wear resistance of the alloy layers with various morphologies differed. The wear resistance order of the different microstructures was: rod-like Fe2B > fishbone-like Fe2B > daisy-like Fe3(C, B) > dendritic Fe. A large number of rod-like Fe2B with high microhardness could be obtained at the boron content of 5.70 5.90 wt.% and the carbon content of 0.50 0.60wt.%. The highest wear resistance of the Fe-B-C alloy layers reached the value of 24.1 g-1, which demonstrates the main microscopic cutting wear mechanism of the Fe-B-C alloy layers.

  3. Nickel acts as an adjuvant during cobalt sensitization.

    Science.gov (United States)

    Bonefeld, Charlotte Menné; Nielsen, Morten Milek; Vennegaard, Marie T; Johansen, Jeanne Duus; Geisler, Carsten; Thyssen, Jacob P

    2015-03-01

    Metal allergy is the most frequent form of contact allergy with nickel and cobalt being the main culprits. Typically, exposure comes from metal-alloys where nickel and cobalt co-exist. Importantly, very little is known about how co-exposure to nickel and cobalt affects the immune system. We investigated these effects by using a recently developed mouse model. Mice were epicutaneously sensitized with i) nickel alone, ii) nickel in the presence of cobalt, iii) cobalt alone, or iv) cobalt in the presence of nickel, and then followed by challenge with either nickel or cobalt alone. We found that sensitization with nickel alone induced more local inflammation than cobalt alone as measured by increased ear-swelling. Furthermore, the presence of nickel during sensitization to cobalt led to a stronger challenge response to cobalt as seen by increased ear-swelling and increased B and T cell responses in the draining lymph nodes compared to mice sensitized with cobalt alone. In contrast, the presence of cobalt during nickel sensitization only induced an increased CD8(+) T cell proliferation during challenge to nickel. Thus, the presence of nickel during cobalt sensitization potentiated the challenge response against cobalt more than the presence of cobalt during sensitization to nickel affected the challenge response against nickel. Taken together, our study demonstrates that sensitization with a mixture of nickel and cobalt leads to an increased immune response to both nickel and cobalt, especially to cobalt, and furthermore that the adjuvant effect appears to correlate with the inflammatory properties of the allergen. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  4. Key parameters having an influence on stress corrosion cracking resistance of alloy 182

    International Nuclear Information System (INIS)

    Steltzlen, F.; Benhamou, C.; Calonne, O.; Brugier, B.; Massoud, J.P.

    2015-01-01

    Nickel-base Alloy 182 has been widely used in nuclear power plants for welds of Alloy 600 components (RPV Bottom Mount Instrumentation and Head Nozzles, Steam Generator Divider Plates...). In service, Alloy 182 shows a better resistance to SCC (Stress Corrosion Cracking) than Alloy 600, but, taking into account operational feedback outside of France, its behavior remains questionable for Long Term Operations. International Field experience and laboratory studies showed that stress relief heat-treated alloy 182 welds result in a better PWSCC resistance than the untreated ones. Trends concerning the following parameters: chemical composition, temperature, stress, surface condition and sampling orientation emerged as influential parameters from preliminary studies. In order to confirm and quantify the effect of the identified key parameters on PWSCC crack initiation, two alloy 182 welds with chemical compositions inducing high and low hot cracking susceptibility and respectively low and high PWSCC susceptibility were investigated. The experimental program included eleven primary water exposures from 5000 up to 15000 hours, in terms of cumulative exposure time, in 3 autoclaves at 3 different operating temperatures (320, 345 and 360 C. degrees). More than 20 various sets of U-bend specimens (6 specimens per set) were tested to investigate 4 stress levels, 2 sampling orientations and 2 surface conditions (grinding on an automatic grinding bench or mechanical polishing). After each successive corrosion test period, optical, dye penetrant tests, XRD measurements and SEM surface examinations were carried out on the specimens. Destructive examinations are performed on the cracked specimens progressively removed from the autoclave and on the un-cracked specimens at the end of the tests. We can draw the following conclusions. The initial weld defects (hot cracking, slag inclusion, mechanical defect...) existing on surface of the specimens did not propagate. Existing weld

  5. Crevice corrosion of corrosion-resistant alloys in simulated sour gas environments

    International Nuclear Information System (INIS)

    Azuma, S.; Kudo, T.

    1991-01-01

    This paper discusses crevice corrosion behaviors of corrosion-resistant alloys (CRAs) with various Ni, Cr, and Mo contents investigated in conditions simulating the sour gas environment encountered in oil and gas production. Crevice corrosion occurred more easily in a 0.1 MPa H 2 S environment than in a 1.0 MPa H 2 S environment. Ni, Cr and Mo all improved crevice corrosion resistance in electrochemical and immersion tests. The improving effect of Ni and Cr on crevice corrosion resistance reached saturation at 20 percent of their contents. Alloys containing more than 6% Mo exhibited excellent crevice corrosion resistance, which could not be achieved by the increment in Ni and Cr contents. The onset of the crevice corrosion on CRAs in H 2 S-Cl - environment was investigated by electrochemically studying the pH drop in the crevice solution and the depassivation pH (pH d ). These are considered to determine the extent of crevice corrosion resistance in comparison to that in O 2 -Cl - environment. It has been shown that the crevice corrosion frequency from the immersion test in 0.1 MPa H 2 S was better correlated with the pH d in the deaerated solution rather than the pH d in the H 2 S containing solution. The crevice corrosion resistance under 0.1 and 1 MPa H 2 S is discussed in relation to the pH d dependent on the H 2 S concentration in the crevice

  6. Hard hardfacing by welding in the manufacture of valves; Problem Cobalt, alternatives, advantages, disadvantages; Recargues Duros por Soldadura en la Fabricacion de Valvulas ; el Problema del Cobalto, alternativas, ventajas, inconvenientes

    Energy Technology Data Exchange (ETDEWEB)

    Piquer Caballero, J.

    2014-07-01

    Alloys of recharge usually used in the field of the valves are base alloys cobalt (stellite), but in the field of nuclear power plants, due to radioactive activation of the cobalt, there is a growing trend to replace these alloys with other calls cobalt free . In this paper we will explore the most frequent and will be deducted the relevant advantages and disadvantages of these, in comparison with base alloys cobalt. (Author)

  7. A biodegradable AZ91 magnesium alloy coated with a thin nanostructured hydroxyapatite for improving the corrosion resistance.

    Science.gov (United States)

    Mukhametkaliyev, T M; Surmeneva, M A; Vladescu, A; Cotrut, C M; Braic, M; Dinu, M; Vranceanu, M D; Pana, I; Mueller, M; Surmenev, R A

    2017-06-01

    The main aim of this study was to investigate the properties of an AZ91 alloy coated with nanostructured hydroxyapatite (HA) prepared by radio frequency (RF) magnetron sputtering. The bioactivity and biomineralization of the AZ91 magnesium alloy coated with HA were investigated in simulated body fluid (SBF) via an in vitro test. Scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, and X-ray diffraction (XRD) analyses were performed. The samples were immersed in SBF to study the ability of the surface to promote the formation of an apatite layer as well as corrosion resistance and mass change of the HA-coated AZ91 alloy. Electrochemical tests were performed to estimate the corrosion behaviour of HA-coated and uncoated samples. The results revealed the capability of the HA coating to significantly improve the corrosion resistance of the uncoated AZ91 alloy. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Temperature and concentration dependences of the electrical resistivity for alloys of plutonium with americium under normal conditions

    Science.gov (United States)

    Tsiovkin, Yu. Yu.; Povzner, A. A.; Tsiovkina, L. Yu.; Dremov, V. V.; Kabirova, L. R.; Dyachenko, A. A.; Bystrushkin, V. B.; Ryabukhina, M. V.; Lukoyanov, A. V.; Shorikov, A. O.

    2010-01-01

    The temperature and concentration dependences of the electrical resistivity for alloys of americium with plutonium are analyzed in terms of the multiband conductivity model for binary disordered substitution-type alloys. For the case of high temperatures ( T > ΘD, ΘD is the Debye temperature), a system of self-consistent equations of the coherent potential approximation has been derived for the scattering of conduction electrons by impurities and phonons without any constraints on the interaction intensity. The definitions of the shift and broadening operator for a single-electron level are used to show qualitatively and quantitatively that the pattern of the temperature dependence of the electrical resistivity for alloys is determined by the balance between the coherent and incoherent contributions to the electron-phonon scattering and that the interference conduction electron scattering mechanism can be the main cause of the negative temperature coefficient of resistivity observed in some alloys involving actinides. It is shown that the great values of the observed resistivity may be attributable to interband transitions of charge carriers and renormalization of their effective mass through strong s-d band hybridization. The concentration and temperature dependences of the resistivity for alloys of plutonium and americium calculated in terms of the derived conductivity model are compared with the available experimental data.

  9. Nano-hardness, wear resistance and pseudoelasticity of hafnium implanted NiTi shape memory alloy.

    Science.gov (United States)

    Zhao, Tingting; Li, Yan; Liu, Yong; Zhao, Xinqing

    2012-09-01

    NiTi shape memory alloy was modified by Hf ion implantation to improve its wear resistance and surface integrity against deformation. The Auger electron spectroscopy and x-ray photoelectron spectroscopy results indicated that the oxide thickness of NiTi alloy was increased by the formation of TiO₂/HfO₂ nanofilm on the surface. The nano-hardness measured by nano-indentation was decreased even at the depth larger than the maximum reach of the implanted Hf ion. The lower coefficient of friction with much longer fretting time indicated the remarkable improvement of wear resistance of Hf implanted NiTi, especially for the sample with a moderate incident dose. The formation of TiO₂/HfO₂ nanofilm with larger thickness and decrease of the nano-hardness played important roles in the improvement of wear resistance. Moreover, Hf implanted NiTi exhibited larger pseudoelastic recovery strain and retained better surface integrity even after being strained to 10% as demonstrated by in situ scanning electron microscope observation. Crown Copyright © 2012. Published by Elsevier Ltd. All rights reserved.

  10. Ultrasonic irradiation and its application for improving the corrosion resistance of phosphate coatings on aluminum alloys.

    Science.gov (United States)

    Sheng, Minqi; Wang, Chao; Zhong, Qingdong; Wei, Yinyin; Wang, Yi

    2010-01-01

    In this paper, ultrasonic irradiation was utilized for improving the corrosion resistance of phosphate coatings on aluminum alloys. The chemical composition and morphology of the coatings were analyzed by X-ray diffraction analysis (XRD) and scanning electron microscopy (SEM). The effect of ultrasonic irradiation on the corrosion resistance of phosphate coatings was investigated by polarization curves and electrochemical impedance spectroscopy (EIS). Various effects of the addition of Nd(2)O(3) in phosphating bath on the performance of the coatings were also investigated. Results show that the composition of phosphate coating were Zn(3)(PO(4))(2).4H(2)O(hopeite) and Zn crystals. The phosphate coatings became denser with fewer microscopic holes by utilizing ultrasonic irradiation treatment. The addition of Nd(2)O(3) reduced the crystallinity of the coatings, with the additional result that the crystallites were increasingly nubby and spherical. The corrosion resistance of the coatings was also significantly improved by ultrasonic irradiation treatment; both the anodic and cathodic processes of corrosion taking place on the aluminum alloy substrate were suppressed consequently. In addition, the electrochemical impedance of the coatings was also increased by utilizing ultrasonic irradiation treatment compared with traditional treatment.

  11. Fracture toughness and corrosion resistance of semisolid AlSi5 alloy

    International Nuclear Information System (INIS)

    Pola, A.; Montesano, L.; Gelfi, M.; Roberti, R.

    2011-01-01

    The aim of this work was to investigate fracture toughness and corrosion resistance of semisolid AlSi5 castings, compared to samples obtained from conventional casting operations. In order to have a semisolid microstructure, the melt alloy was treated by means of ultrasound during solidification and then poured into permanent moulds. Mechanical properties of semisolid and conventional castings were compared by means of ultimate tensile strength (R m ), yield stress (Rp 02 ) and hardness (HV) measurements. Fracture mechanics tests were carried out on Single Edge Notched Bend (SENB) specimens, machined from castings, and pre-cracked by fatigue. These tests were performed to determine the effect of the microstructure on the J-Integral resistance (J-R) behavior and to deeply understand the ductile fracture behaviour of semisolid parts. The J-Integral versus spaced crack extension (J-Δa) curves showed an improved resistance of the semisolid microstructure, due to the higher ductility. Finally, the corrosion behaviour of semisolid samples was compared to that of castings coming from solidification of fully liquid alloy by means of electrochemical potentiodynamic polarization tests. It was observed that the globular microstructure offers better quality, in terms of higher mechanical properties, as a consequence of a more uniform distribution of the solute.

  12. High corrosion resistance of austenitic stainless steel alloyed with nitrogen in an acid solution

    Energy Technology Data Exchange (ETDEWEB)

    Metikos-Hukovic, M., E-mail: mmetik@fkit.h [Department of Electrochemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Savska 16, P.O. Box 177, 100000 Zagreb (Croatia); Babic, R. [Department of Electrochemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Savska 16, P.O. Box 177, 100000 Zagreb (Croatia); Grubac, Z. [Department of General and Inorganic Chemistry, Faculty of Chemistry and Technology, University of Split, 21000 Split (Croatia); Petrovic, Z. [Department of Electrochemistry, Faculty of Chemical Engineering and Technology, University of Zagreb, Savska 16, P.O. Box 177, 100000 Zagreb (Croatia); Lajci, N. [Faculty of Mine and Metallurgy, University of Prishtina, 10000 Prishtina, Kosovo (Country Unknown)

    2011-06-15

    Highlights: {yields} ASS alloyed with nitrogen treated at 1150 {sup o}C exhibits microstructure homogeneity. {yields} Passivation peak of ASS corresponds to oxidation of metal and absorbed hydrogen. {yields} Transfer phenomena and conductivity depend on the film formation potential. {yields} Electronic structure of the passive film and its corrosion resistance correlate well. {yields} Passive film on ASS with nitrogen is low disordered and high corrosion resistant. - Abstract: Passivity of austenitic stainless steel containing nitrogen (ASS N25) was investigated in comparison with AISI 316L in deareated acid solution, pH 0.4. A peculiar nature of the passivation peak in a potentiodynamic curve and the kinetic parameters of formation and growth of the oxide film have been discussed. The electronic-semiconducting properties of the passive films have been correlated with their corrosion resistance. Alloying austenitic stainless steel with nitrogen increases its microstructure homogeneity and decreases the concentration of charge carriers, which beneficially affects the protecting and electronic properties of the passive oxide film.

  13. Outstanding resistance and passivation behaviour of new Fe-Co metal-metal glassy alloys in alkaline media.

    Directory of Open Access Journals (Sweden)

    Khadijah M Emran

    Full Text Available The electrochemical behavior of the oxide layers on two metal-metal glassy alloys, Fe78Co9Cr10Mo2Al1 (VX9and Fe49Co49V2 (VX50 (at.%, were studied using electrochemical techniques including electrochemical frequency modulation (EFM, electrochemical impedance spectroscopy (EIS and cyclic polarization (CP measurements. The morphology and composition of the alloy surfaces were investigated using X-ray photoelectron spectroscopy (XPS, scanning electron microscopy (SEM and atomic force microscopy (AFM. The corrosion rate and surface roughness of both alloys increased as the concentration of NaOH in aqueous solution was raised. The presence of some protective elements in the composition of the alloys led to the formation of a spontaneous passive layer on the alloy surface. The higher resistance values of both alloys were associated with the magnitude of the dielectric properties of the passive films formed on their surfaces. Both alloys are classified as having outstanding resistance to corrosion, which results from the formation of a passive film that acts as an efficient barrier to corrosion in alkaline solution.

  14. Outstanding resistance and passivation behaviour of new Fe-Co metal-metal glassy alloys in alkaline media.

    Science.gov (United States)

    Emran, Khadijah M; Al-Harbi, Albandaree K

    2018-01-01

    The electrochemical behavior of the oxide layers on two metal-metal glassy alloys, Fe78Co9Cr10Mo2Al1 (VX9)and Fe49Co49V2 (VX50) (at.%), were studied using electrochemical techniques including electrochemical frequency modulation (EFM), electrochemical impedance spectroscopy (EIS) and cyclic polarization (CP) measurements. The morphology and composition of the alloy surfaces were investigated using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). The corrosion rate and surface roughness of both alloys increased as the concentration of NaOH in aqueous solution was raised. The presence of some protective elements in the composition of the alloys led to the formation of a spontaneous passive layer on the alloy surface. The higher resistance values of both alloys were associated with the magnitude of the dielectric properties of the passive films formed on their surfaces. Both alloys are classified as having outstanding resistance to corrosion, which results from the formation of a passive film that acts as an efficient barrier to corrosion in alkaline solution.

  15. Experimental study on the resistance to hydrogen embrittlement of NIFS-V4Cr4Ti alloy

    International Nuclear Information System (INIS)

    Chen Jiming; Xu Zengyu; Den Ying; Muroga, T.

    2002-01-01

    SWIP (Southwestern Institute of Physics) has joined an international collaboration on the hydrogen embrittlement resistance evaluation of the vanadium alloy. This paper presents some experiments on the tensile properties and Charpy impact properties of the NIFS-V4Cr4Ti alloy with high-level hydrogen concentration. The experiment results show different properties against hydrogen embrittlement in static tension and impact load. The critical hydrogen concentration required to embrittle the alloy was about 215 - 310 mg·kg -1 on static tension load, but less than 130 mg·kg -1 on impact loading

  16. The cyclic oxidation resistance at 1200 C of Beta-NiAl, FeAl, and CoAl alloys with selected third element additions

    International Nuclear Information System (INIS)

    Barrett, C.A.; Titran, R.H.

    1992-04-01

    The intermetallic compounds Beta-NiAl, FeAl, and CoAl were tested in cyclic oxidation with selected third element alloy additions. Tests in static air for 200 1-hr cycles at 1200 C indicated by specific weight change/time data and x-ray diffraction analysis that the 5 at percent alloy additions did not significantly improve the oxidation resistance over the alumina forming baseline alloys without the additions. Many of the alloy additions were actually deleterious. Ta and Nb were the only alloy additions that actually altered the nature of the oxide(s) formed and still maintained the oxidation resistance of the protective alumina scale

  17. Cobalt-free nickel-base superalloys

    International Nuclear Information System (INIS)

    Koizumi, Yutaka; Yamazaki, Michio; Harada, Hiroshi

    1979-01-01

    Cobalt-free nickel-base cast superalloys have been developed. Cobalt is considered to be a beneficial element to strengthen the alloys but should be eliminated in alloys to be used for direct cycle helium turbine driven by helium gas from HTGR (high temp. gas reactor). The elimination of cobalt is required to avoid the formation of radioactive 60 Co from the debris or scales of the alloys. Cobalt-free alloys are also desirable from another viewpoint, i.e. recently the shortage of the element has become a serious problem in industry. Cobalt-free Mar-M200 type alloys modified by the additions of 0.15 - 0.2 wt% B and 1 - 1.5 wt% Hf were found to have a creep rupture strength superior or comparable to that of the original Mar-M200 alloy bearing cobalt. The ductility in tensile test at 800 0 C, as cast or after prolonged heating at 900 0 C (the tensile test was done without removing the surface layer affected by the heating), was also improved by the additions of 0.15 - 0.2% B and 1 - 1.5% Hf. The morphology of grain boundaries became intricated by the additions of 0.15 - 0.2% B and 1 - 1.5% Hf, to such a degree that one can hardly distinguish grain boundaries by microscopes. The change in the grain boundary morphology was considered, as suggested previously by one of the authors (M.Y.), to be the reason for the improvements in the creep rupture strength and tensile ductility. (author)

  18. Structure of Ti-6Al-4V nanostructured titanium alloy joint obtained by resistance spot welding

    Science.gov (United States)

    Klimenov, V. A.; Kurgan, K. A.; Chumaevskii, A. V.; Klopotov, A. A.; Gnyusov, S. F.

    2016-01-01

    The structure of weld joints of the titanium alloy Ti-6Al-4V in the initial ultrafine-grained state, obtained by resistance spot welding, is studied using the optical and scanning electron microscopy method and the X-ray structure analysis. The carried out studies show the relationship of the metal structure in the weld zone with main joint zones. The structure in the core zone and the heat affected zone is represented by finely dispersed grains of needle-shaped martensite, differently oriented in these zones. The change in the microhardness in the longitudinal section of the weld joint clearly correlates with structural changes during welding.

  19. Effects of heat treatment on properties of multi-element low alloy wear-resistant steel

    Directory of Open Access Journals (Sweden)

    SONG Xu-ding

    2007-02-01

    Full Text Available The paper has studied the mechanical properties and heat treatment effects on multi-element low alloy wear-resistant steel (MLAWS used as a material for the liner of rolling mill torii. The results show that when quenched at 900-920℃ and tempered at 350-370℃, the MLAWS has achieved hardness above 60 HRC, tensile strength greater than 1 600 MPa, impact toughness higher than 18J/cm2 and fracture toughness greater than 37 MPa

  20. Structure of Ti-6Al-4V nanostructured titanium alloy joint obtained by resistance spot welding

    Energy Technology Data Exchange (ETDEWEB)

    Klimenov, V. A., E-mail: klimenov@tpu.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation); Kurgan, K. A., E-mail: kirill-k2.777@mail.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); Chumaevskii, A. V., E-mail: tch7av@gmail.com [Institute of Strength Physics and Materials Science, Siberian Branch of the Russian Academy of Sciences, 2/4 Akademicheskii pr., Tomsk, 634021 (Russian Federation); Klopotov, A. A., E-mail: klopotovaa@tsuab.ru [Tomsk State University of Architecture and Building, 2 Solyanaya Sq, Tomsk, 634003 (Russian Federation); National Research Tomsk State University, 36 Lenin Ave., Tomsk, 634050 (Russian Federation); Gnyusov, S. F., E-mail: gnusov@rambler.ru [National Research Tomsk Polytechnic University, 30 Lenin Av., Tomsk, 634050 (Russian Federation)

    2016-01-15

    The structure of weld joints of the titanium alloy Ti-6Al-4V in the initial ultrafine-grained state, obtained by resistance spot welding, is studied using the optical and scanning electron microscopy method and the X-ray structure analysis. The carried out studies show the relationship of the metal structure in the weld zone with main joint zones. The structure in the core zone and the heat affected zone is represented by finely dispersed grains of needle-shaped martensite, differently oriented in these zones. The change in the microhardness in the longitudinal section of the weld joint clearly correlates with structural changes during welding.

  1. Boron and Zirconium from Crucible Refractories in a Complex Heat-Resistant Alloy

    Science.gov (United States)

    Decker, R F; Rowe, John P; Freeman, J W

    1958-01-01

    In a laboratory study of the factors involved in the influence of induction vacuum melting on 55ni-20cr-15co-4mo-3ti-3al heat resistant alloy, it was found that the major factor was the type of ceramic used as the crucible. The study concluded that trace amounts of boron or zirconium derived from reaction of the melt with the crucible refactories improved creep-rupture properties at 1,600 degrees F. Boron was most effective and, in addition, markedly improved hot-workability.

  2. Evaluation and comparison of shear bond strength of porcelain to a beryllium-free alloy of nickel-chromium, nickel and beryllium free alloy of cobalt-chromium, and titanium: An in vitro study

    Directory of Open Access Journals (Sweden)

    Ananya Singh

    2017-01-01

    Conclusion: It could be concluded that newer nickel and beryllium free Co-Cr alloys and titanium alloys with improved strength to weight ratio could prove to be good alternatives to the conventional nickel-based alloys when biocompatibility was a concern.

  3. Corrosion resistance and in vitro response of laser-deposited Ti-Nb-Zr-Ta alloys for orthopedic implant applications.

    Science.gov (United States)

    Samuel, Sonia; Nag, Soumya; Nasrazadani, Seifollah; Ukirde, Vaishali; El Bouanani, Mohamed; Mohandas, Arunesh; Nguyen, Kytai; Banerjee, Rajarshi

    2010-09-15

    While direct metal deposition of metallic powders, via laser deposition, to form near-net shape orthopedic implants is an upcoming and highly promising technology, the corrosion resistance and biocompatibility of such novel metallic biomaterials is relatively unknown and warrants careful investigation. This article presents the results of some initial studies on the corrosion resistance and in vitro response of laser-deposited Ti-Nb-Zr-Ta alloys. These new generation beta titanium alloys are promising due to their low elastic modulus as well as due the fact that they comprise of completely biocompatible alloying elements. The results indicate that the corrosion resistance of these laser-deposited alloys is comparable and in some cases even better than the currently used commercially-pure (CP) titanium (Grade 2) and Ti-6Al-4V ELI alloys. The in vitro studies indicate that the Ti-Nb-Zr-Ta alloys exhibit comparable cell proliferation but enhanced cell differentiation properties as compared with Ti-6Al-4V ELI. (c) 2010 Wiley Periodicals, Inc.

  4. Improved stress corrosion cracking resistance of a novel biodegradable EW62 magnesium alloy by rapid solidification, in simulated electrolytes.

    Science.gov (United States)

    Hakimi, O; Aghion, E; Goldman, J

    2015-06-01

    The high corrosion rate of magnesium (Mg) and Mg-alloys precludes their widespread acceptance as implantable biomaterials. Here, we investigated the potential for rapid solidification (RS) to increase the stress corrosion cracking (SCC) resistance of a novel Mg alloy, Mg-6%Nd-2%Y-0.5%Zr (EW62), in comparison to its conventionally cast (CC) counterpart. RS ribbons were extrusion consolidated in order to generate bioimplant-relevant geometries for testing and practical use. Microstructural characteristics were examined by SEM. Corrosion rates were calculated based upon hydrogen evolution during immersion testing. The surface layer of the tested alloys was analyzed by X-ray photoelectron spectroscopy (XPS). Stress corrosion resistance was assessed by slow strain rate testing and fractography. The results indicate that the corrosion resistance of the RS alloy is significantly improved relative to the CC alloy due to a supersaturated Nd enrichment that increases the Nd2O3 content in the external oxide layer, as well as a more homogeneous structure and reduced grain size. These improvements contributed to the reduced formation of hydrogen gas and hydrogen embrittlement, which reduced the SCC sensitivity relative to the CC alloy. Therefore, EW62 in the form of a rapidly solidified extruded structure may serve as a biodegradable implant for biomedical applications. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Improvements in the corrosion resistance and biocompatibility of biomedical Ti–6Al–7Nb alloy using an electrochemical anodization treatment

    International Nuclear Information System (INIS)

    Huang, Her-Hsiung; Wu, Chia-Ping; Sun, Ying-Sui; Lee, Tzu-Hsin

    2013-01-01

    The biocompatibility of an implant material is determined by its surface characteristics. This study investigated the application of an electrochemical anodization surface treatment to improve both the corrosion resistance and biocompatibility of Ti–6Al–7Nb alloy for implant applications. The electrochemical anodization treatment produced an Al-free oxide layer with nanoscale porosity on the Ti–6Al–7Nb alloy surface. The surface topography and microstructure of Ti–6Al–7Nb alloy were analyzed. The corrosion resistance was investigated using potentiodynamic polarization curve measurements in simulated blood plasma (SBP). The adhesion and proliferation of human bone marrow mesenchymal stem cells to test specimens were evaluated using various biological analysis techniques. The results showed that the presence of a nanoporous oxide layer on the anodized Ti–6Al–7Nb alloy increased the corrosion resistance (i.e., increased the corrosion potential and decreased both the corrosion rate and the passive current) in SBP compared with the untreated Ti–6Al–7Nb alloy. Changes in the nanotopography also improved the cell adhesion and proliferation on the anodized Ti–6Al–7Nb alloy. We conclude that a fast and simple electrochemical anodization surface treatment improves the corrosion resistance and biocompatibility of Ti–6Al–7Nb alloy for biomedical implant applications. - Highlights: ► Simple/fast electrochemical anodization was applied to biomedical Ti–6Al–7Nb surface. ► Anodized surface had nano-porous topography and contained Al-free oxide layer. ► Anodized surface raised corrosion resistance in three simulated biological solutions. ► Anodized surface enhanced cell adhesion and cell proliferation. ► Electrochemical anodization has potential as biomedical implant surface treatment

  6. Theoretical basis for unified analysis of experimental data and design of swelling-resistant alloys

    International Nuclear Information System (INIS)

    Mansur, L.K.; Lee, E.H.

    1991-01-01

    Essential aspects of the theory of radiation-induced swelling are reviewed. In particular, concepts central to the understanding of experimental data and the control of swelling by alloy design are discussed. The knowledge that a critical number of gas atoms is required in a cavity before point defect-driven swelling can begin is a most important contribution of theory. The mathematical expression that have been derived for calculating this critical quantity are given in terms of materials parameters and irradiation conditions. After swelling begins, its magnitude as a function of dose is governed strongly by the relative sink strengths for point defects of dislocations and cavities, expressed in terms of an index of the microstructure, Q. Hich swelling and low swelling microstructures can be categorized into four types based on this index. Wide ranges of experimental swelling results covering ferritic/martensite and austenitic alloys, neutron and ion irradiations and a variety of compositions and irradiation conditions are analyzed and found to be explained consistently within this framework. Based on the understanding gained, approaches to alloy design for swelling resistance are recommended. (orig.)

  7. Radiation Resistance of the U(Al, Si)₃ Alloy: Ion-Induced Disordering.

    Science.gov (United States)

    Meshi, Louisa; Yaniv, Gili; Horak, Pavel; Vacik, Jiri; Mykytenko, Natalia; Rafailov, Gennady; Dahan, Itzchak; Fuks, David; Kiv, Arik

    2018-02-02

    During the exploitation of nuclear reactors, various U-Al based ternary intermetallides are formed in the fuel-cladding interaction layer. Structure and physical properties of these intermetallides determine the radiation resistance of cladding and, ultimately, the reliability and lifetime of the nuclear reactor. In current research, U(Al, Si)₃ composition was studied as a potential constituent of an interaction layer. Phase content of the alloy of an interest was ordered U(Al, Si)₃, structure of which was reported earlier, and pure Al (constituting less than 20 vol % of the alloy). This alloy was investigated prior and after the irradiation performed by Ar ions at 30 keV. The irradiation was performed on the transmission electron microscopy (TEM, JEOL, Japan) samples, characterized before and after the irradiation process. Irradiation induced disorder accompanied by stress relief. Furthermore, it was found that there is a dose threshold for disordering of the crystalline matter in the irradiated region. Irradiation at doses equal or higher than this threshold resulted in almost solely disordered phase. Using the program "Stopping and Range of Ions in Matter" (SRIM), the parameters of penetration of Ar ions into the irradiated samples were estimated. Based on these estimations, the dose threshold for ion-induced disordering of the studied material was assessed.

  8. Radiation Resistance of the U(Al, Si3 Alloy: Ion-Induced Disordering

    Directory of Open Access Journals (Sweden)

    Louisa Meshi

    2018-02-01

    Full Text Available During the exploitation of nuclear reactors, various U-Al based ternary intermetallides are formed in the fuel-cladding interaction layer. Structure and physical properties of these intermetallides determine the radiation resistance of cladding and, ultimately, the reliability and lifetime of the nuclear reactor. In current research, U(Al, Si3 composition was studied as a potential constituent of an interaction layer. Phase content of the alloy of an interest was ordered U(Al, Si3, structure of which was reported earlier, and pure Al (constituting less than 20 vol % of the alloy. This alloy was investigated prior and after the irradiation performed by Ar ions at 30 keV. The irradiation was performed on the transmission electron microscopy (TEM, JEOL, Japan samples, characterized before and after the irradiation process. Irradiation induced disorder accompanied by stress relief. Furthermore, it was found that there is a dose threshold for disordering of the crystalline matter in the irradiated region. Irradiation at doses equal or higher than this threshold resulted in almost solely disordered phase. Using the program “Stopping and Range of Ions in Matter” (SRIM, the parameters of penetration of Ar ions into the irradiated samples were estimated. Based on these estimations, the dose threshold for ion-induced disordering of the studied material was assessed.

  9. Dynamic Recrystallization Behavior and Corrosion Resistance of a Dual-Phase Mg-Li Alloy.

    Science.gov (United States)

    Liu, Gang; Xie, Wen; Wei, Guobing; Yang, Yan; Liu, Junwei; Xu, Tiancai; Xie, Weidong; Peng, Xiaodong

    2018-03-09

    The hot deformation and dynamic recrystallization behavior of the dual-phase Mg-9Li-3Al-2Sr-2Y alloy had been investigated using a compression test. The typical dual-phase structure was observed, and average of grain size of as-homogenized alloy is about 110 µm. It mainly contains β-Li, α-Mg, Al₄Sr and Al₂Y phases. The dynamic recrystallization (DRX) kinetic was established based on an Avrami type equation. The onset of the DRX process occurred before the peak of the stress-strain flow curves. It shows that the DRX volume fraction increases with increasing deformation temperature or decreasing strain rate. The microstructure evolution during the hot compression at various temperatures and strain rates had been investigated. The DRX grain size became larger with the increasing testing temperature or decreasing strain rate because the higher temperature or lower strain rate can improve the migration of DRX grain boundaries. The fully recrystallized microstructure can be achieved in a small strain due to the dispersed island-shape α-Mg phases, continuous the Al₄Sr phases and spheroidal Al₂Y particles, which can accelerate the nucleation. The continuous Al₄Sr phases along the grain boundaries are very helpful for enhancing the corrosion resistance of the duplex structured Mg-Li alloy, which can prevent the pitting corrosion and filiform corrosion.

  10. Crevice corrosion resistance of Ni-Cr-Mo alloys as engineered barriers in nuclear waste repositories

    International Nuclear Information System (INIS)

    Hornus, E. C.; Carranza, R. M.; Giordano, C. M.; Rodríguez, M. A.; Rebak, R. B.

    2013-01-01

    The crevice corrosion re passivation potential was determined by the Potentiodynamic- Galvanostatic-Potentiodynamic (PD-GS-PD) method. Alloys 625, C-22, C-22HS and HYBRID-BC1 were used. Specimens contained 24 artificially creviced spots formed by a ceramic washer (crevice former) wrapped with a PTFE tape. Crevice corrosion tests were performed in 0,1 mol/L and 1 mol/L NaCl solutions at temperatures between 20 and 90ºC, and CaCl2 5 mol/L solution at temperatures between 20 and 117°C. The crevice corrosion resistance of the alloys increased in the following order: 625 < C-22 < C-22HS < HYBRID-BC1. The repassivation potential (ECO) showed the following relationship with temperature (T) and chloride concentration ([Cl-]) ECO = (A + B T) log [Cl-] + C T + D; where A, B, C and D are constants. At temperatures above 90°C, ECO for alloy 625 stabilized at a minimum value of -0.26 VSCE (author)

  11. Solid solution strengthening and diffusion in nickel- and cobalt-based superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Rehman, Hamad ur

    2016-07-01

    Nickel and cobalt-based superalloys with a γ-γ{sup '} microstructure are known for their excellent creep resistance at high temperatures. Their microstructure is engineered using different alloying elements, that partition either to the fcc γ matrix or to the ordered γ{sup '} phase. In the present work the effect of alloying elements on their segregation behaviour in nickel-based superalloys, diffusion in cobalt-based superalloys and the temperature dependent solid solution strengthening in nickel-based alloys is investigated. The effect of dendritic segregation on the local mechanical properties of individual phases in the as-cast, heat treated and creep deformed state of a nickel-based superalloy is investigated. The local chemical composition is characterized using Electron Probe Micro Analysis and then correlated with the mechanical properties of individual phases using nanoindentation. Furthermore, the temperature dependant solid solution hardening contribution of Ta, W and Re towards fcc nickel is studied. The room temperature hardening is determined by a diffusion couple approach using nanoindentation and energy dispersive X-ray analysis for relating hardness to the chemical composition. The high temperature properties are determined using compression strain rate jump tests. The results show that at lower temperatures, the solute size is prevalent and the elements with the largest size difference with nickel, induce the greatest hardening consistent with a classical solid solution strengthening theory. At higher temperatures, the solutes interact with the dislocations such that the slowest diffusing solute poses maximal resistance to dislocation glide and climb. Lastly, the diffusion of different technically relevant solutes in fcc cobalt is investigated using diffusion couples. The results show that the large atoms diffuse faster in cobalt-based superalloys similar to their nickel-based counterparts.

  12. Solid solution strengthening and diffusion in nickel- and cobalt-based superalloys

    International Nuclear Information System (INIS)

    Rehman, Hamad ur

    2016-01-01

    Nickel and cobalt-based superalloys with a γ-γ ' microstructure are known for their excellent creep resistance at high temperatures. Their microstructure is engineered using different alloying elements, that partition either to the fcc γ matrix or to the ordered γ ' phase. In the present work the effect of alloying elements on their segregation behaviour in nickel-based superalloys, diffusion in cobalt-based superalloys and the temperature dependent solid solution strengthening in nickel-based alloys is investigated. The effect of dendritic segregation on the local mechanical properties of individual phases in the as-cast, heat treated and creep deformed state of a nickel-based superalloy is investigated. The local chemical composition is characterized using Electron Probe Micro Analysis and then correlated with the mechanical properties of individual phases using nanoindentation. Furthermore, the temperature dependant solid solution hardening contribution of Ta, W and Re towards fcc nickel is studied. The room temperature hardening is determined by a diffusion couple approach using nanoindentation and energy dispersive X-ray analysis for relating hardness to the chemical composition. The high temperature properties are determined using compression strain rate jump tests. The results show that at lower temperatures, the solute size is prevalent and the elements with the largest size difference with nickel, induce the greatest hardening consistent with a classical solid solution strengthening theory. At higher temperatures, the solutes interact with the dislocations such that the slowest diffusing solute poses maximal resistance to dislocation glide and climb. Lastly, the diffusion of different technically relevant solutes in fcc cobalt is investigated using diffusion couples. The results show that the large atoms diffuse faster in cobalt-based superalloys similar to their nickel-based counterparts.

  13. Electrochemical behavior and corrosion resistance of Ti-15Mo alloy in naturally-aerated solutions, containing chloride and fluoride ions.

    Science.gov (United States)

    Rodrigues, A V; Oliveira, N T C; dos Santos, M L; Guastaldi, A C

    2015-01-01

    The electrochemical behavior and corrosion resistance of Ti-15Mo alloy to applications as biomaterials in solutions 0.15 mol L(-1) Ringer, 0.15 mol L(-1) Ringer plus 0.036 mol L(-1) NaF and 0.036 mol L(-1) NaF (containing 1,500 ppm of fluoride ions, F(-)) were investigated using open-circuit potential, cyclic voltammetry, and electrochemical impedance spectroscopy techniques, X-ray photoelectron spectroscopy and scanning electron microscope. Corrosion resistance and electrochemical stability of the Ti-15Mo alloy decreased in solutions containing F(-) ions. In all cases, there were formation and growth of TiO2 and MoO3 (a protector film), not being observed pitting corrosion, which might enable Ti-15Mo alloys to be used as biomedical implant, at least in the studied conditions, since the electrochemical stability and corrosion resistance of the passive films formed are necessary conditions for osseointegration.

  14. Improving the corrosion resistance of Mg-4.0Zn-0.2Ca alloy by micro-arc oxidation.

    Science.gov (United States)

    Xia, Y H; Zhang, B P; Lu, C X; Geng, L

    2013-12-01

    In this paper, corrosion resistance of the Mg-4.0Zn-0.2Ca alloy was modified by micro-arc oxidation (MAO) process. The microstructure and phase constituents of MAO layer were characterized by SEM, XRD and X-ray photoelectron spectroscopy (XPS). The corrosion resistance of MAO treated Mg-4.0Zn-0.2Ca alloy in the simulated body fluid were characterized by potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) techniques. The microstructure results indicated that a kind of ceramic film was composed by MgO and MgF2 was formed on the surface of Mg-4.0Zn-0.2Ca alloy after MAO treatment. The electrochemical test reveals that the corrosion resistance of MAO treated samples increase 1 order of magnitude. The mechanical intensity test showed that the MAO treated samples has suitable mechanical properties. © 2013.

  15. Corrosion resistance assessment of Co-Cr alloy frameworks fabricated by CAD/CAM milling, laser sintering, and casting methods.

    Science.gov (United States)

    Tuna, Süleyman Hakan; Özçiçek Pekmez, Nuran; Kürkçüoğlu, Işin

    2015-11-01

    The effects of fabrication methods on the corrosion resistance of frameworks produced with Co-Cr alloys are not clear. The purpose of this in vitro study was to evaluate the electrochemical corrosion resistance of Co-Cr alloy specimens that were fabricated by conventional casting, milling, and laser sintering. The specimens fabricated with 3 different methods were investigated by potentiodynamic tests and electrochemical impedance spectroscopy in an artificial saliva. Ions released into the artificial saliva were estimated with inductively coupled plasma-mass spectrometry, and the results were statistically analyzed. The specimen surfaces were investigated with scanning electron microscopy before and after the tests. In terms of corrosion current and Rct properties, statistically significant differences were found both among the means of the methods and among the means of the material groups (Pcorrosion than those produced by milling and laser sintering. The corrosion resistance of a Co-Cr alloy specimens fabricated by milling or laser sintering was greater than that of the conventionally cast alloy specimens. The Co-Cr specimens produced by the same method also differed from one another in terms of corrosion resistance. These differences may be related to the variations in the alloy compositions. Copyright © 2015 Editorial Council for the Journal of Prosthetic Dentistry. Published by Elsevier Inc. All rights reserved.

  16. Radiation Tolerance of Controlled Fusion Welds in High Temperature Oxidation Resistant FeCrAl Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Gussev, Maxim N. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Field, Kevin G. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2017-08-01

    High temperature oxidation resistant iron-chromium-aluminum (FeCrAl) alloys are candidate alloys for nuclear applications due to their exceptional performance during off-normal conditions such as a loss-of-coolant accident (LOCA) compared to currently deployed zirconium-based claddings [1]. A series of studies have been completed to determine the weldability of the FeCrAl alloy class and investigate the weldment performance in the as-received (non-irradiated) state [2,3]. These initial studies have shown the general effects of composition and microstructure on the weldability of FeCrAl alloys. Given this, limited details on the radiation tolerance of FeCrAl alloys and their weldments exist. Here, the highest priority candidate FeCrAl alloys and their weldments have been investigated after irradiation to enable a better understanding of FeCrAl alloy weldment performance within a high-intensity neutron field. The alloys examined include C35M (Fe-13%Cr-5% Al) and variants with aluminum (+2%) or titanium carbide (+1%) additions. Two different sub-sized tensile geometries, SS-J type and SS-2E (or SS-mini), were neutron irradiated in the High Flux Isotope Reactor to 1.8-1.9 displacements per atom (dpa) in the temperature range of 195°C to 559°C. Post irradiation examination of the candidate alloys was completed and included uniaxial tensile tests coupled with digital image correlation (DIC), scanning electron microscopy-electron back scattered diffraction analysis (SEM-EBSD), and SEM-based fractography. In addition to weldment testing, non-welded parent material was examined as a direct comparison between welded and non-welded specimen performance. Both welded and non-welded specimens showed a high degree of radiation-induced hardening near irradiation temperatures of 200°C, moderate radiation-induced hardening near temperatures of 360°C, and almost no radiation-induced hardening at elevated temperatures near 550°C. Additionally, low-temperature irradiations showed

  17. Multi-wall carbon nanotube-embedded lithium cobalt phosphate composites with reduced resistance for high-voltage lithium-ion batteries

    Science.gov (United States)

    Kim, Tae Kyoung; Rustomji, Cyrus S.; Cho, Hyung-Man; Chun, Dongwon; Jung, Jae-Young; Caldwell, Elizabeth; Kim, Youngjin; Han, Jun Hyun; Jin, Sungho

    2016-01-01

    Lithium cobalt phosphate (LCP) is a high-voltage cathode material used in highenergy- density lithium-ion batteries. With a novel composite synthesis method, multi-wall carbon nanotube (MWCNT)-embedded LCP nanocomposites (LCPCNT composites) are synthesized to enhance the electrical conductance of LCP particles, reducing charge-transfer resistance. The LCP-CNT composites with enhanced electrical conductance approximately doubled cell capacity compared to a cell with a bare LCP cathode. The crystal structure of LCP-CNT composite particles is characterized by X-ray diffraction; the microstructures of the embedded MWCNTs inside LCP particles are confirmed by transmission and scanning electron microscopy with focused ion beam procedures. Electrochemical impedance spectroscopy shows the charge-transfer resistance of the cell with the LCP-CNT composite (1.0 wt. % CNT) cathode decreases to ~80 Ω, much smaller than the ~150 Ω charge-transfer resistance of the bare-LCP cathode cell. Based on battery test and impedance analysis, the main factors affecting the capacity increment are the reduced charge transfer resistance and the uniform distribution of MWCNTs, which is formed during the gelation step of the LCP synthesis procedure. [Figure not available: see fulltext.

  18. Influence of a niobium coating on sulfidation resistance of FeCr and FeCrY alloys

    International Nuclear Information System (INIS)

    Geribola, Gulherme Altomari

    2014-01-01

    Niobium and niobium based alloys are currently used in many industrial applications because they offer excellent resistance to degradation in various corrosive environments. These media include gaseous atmospheres at high temperatures such as those found in existing coal gasifying plants in power plants for energy generation. These atmospheres are complex gas mixtures that contain sulfur and oxygen, among other compounds. Sulphides are thermodynamically less stable, have lower melting points and often have larger deviations from stoichiometry compared to the corresponding oxides. Although there are studies regarding the use of refractory metals in high temperature sulphidizing atmospheres, the use of niobium compounds has not been adequately evaluated and there is very little studies available in the literature about its use as a protective coating. The aim of this study was to evaluate the effect of a niobium film, deposited by magnetron sputtering on the isothermal sulphidation behavior of Fe-20Cr and Fe-20Cr-1Y alloys. The sulphidation tests were carried out at 500, 600 and 700 deg C for 2h in H 2 /2% H2S atmosphere. The sulphidation resistance was determined by mass gain per unit area. The sulphidation behavior of the coated and uncoated alloys was similar at 500 deg C, and none of the alloys scaled. At 700 deg C FeCr alloy scaled in the form of a fine powder, while the reaction product formed on the alloy FeCrY scaled in the form of plates. The effect of niobium became pronounced at 700 deg C. The reaction product layer formed on the coated alloy was thinner and more plastic than that formed on the uncoated alloy. The mass gain per unit area of the coated alloys decreased significantly and they did not scaled. (author)

  19. Microstructures, mechanical properties and corrosion resistance of the Zr−xTi (Ag) alloys for dental implant application

    International Nuclear Information System (INIS)

    Cui, W.F.; Liu, N.; Qin, G.W.

    2016-01-01

    The Zr−xTi (Ag) alloys were designed for the application of dental implants. The microstructures of Zr−20Ti and Zr−40Ti alloy were observed using optical microscope and transmission electronic microscope. The hardness and compressive tests were performed to evaluate the mechanical properties of the Zr−xTi alloys. The electrochemical behavior of the Zr−xTi alloys with and without 6% Ag was investigated in the acidified artificial saliva containing 0.1% NaF (pH = 4). For comparison, the electrochemical behavior of cp Ti was examined in the same condition. The results show that the quenched Zr−20Ti and Zr−40Ti alloy exhibit acicular martensite microstructures containing twin substructure. They display good mechanical properties with the hardness of ∼330HV, the yield strength of ∼1000 MPa and the strain to fracture of ∼25% at room temperature. Adding 6% Ag to Zr−20Ti alloy enhances the passivity breakdown potential and the self-corrosion potential, but hardly affects the corrosion current density and the impedance modulus. 6% Ag in Zr−40Ti alloy distinctly increases pitting corrosion resistance, which is attributed the formation of thick, dense and stable passive film under the joint action of titanium and silver. In comparison with cp Ti, Zr−40Ti−6Ag alloy possesses the same good corrosion resistance in the rigorous oral environment as well as the superior mechanical properties. - Highlights: • The quenched Zr20Ti and Zr40Ti obtain acicular martensite microstructure. • Zr20Ti and Zr40Ti possess high hardness, strength and strain to fracture. • Increasing Ti content decreases corrosion current density. • Adding Ag enhances passivation breakdown potentials of Zr20Ti and Zr40Ti. • Zr40Ti6Ag has optimum mechanical properties and pitting corrosion resistance.

  20. Microstructures, mechanical properties and corrosion resistance of the Zr−xTi (Ag) alloys for dental implant application

    Energy Technology Data Exchange (ETDEWEB)

    Cui, W.F., E-mail: cuiwf@atm.neu.edu.cn; Liu, N.; Qin, G.W.

    2016-06-15

    The Zr−xTi (Ag) alloys were designed for the application of dental implants. The microstructures of Zr−20Ti and Zr−40Ti alloy were observed using optical microscope and transmission electronic microscope. The hardness and compressive tests were performed to evaluate the mechanical properties of the Zr−xTi alloys. The electrochemical behavior of the Zr−xTi alloys with and without 6% Ag was investigated in the acidified artificial saliva containing 0.1% NaF (pH = 4). For comparison, the electrochemical behavior of cp Ti was examined in the same condition. The results show that the quenched Zr−20Ti and Zr−40Ti alloy exhibit acicular martensite microstructures containing twin substructure. They display good mechanical properties with the hardness of ∼330HV, the yield strength of ∼1000 MPa and the strain to fracture of ∼25% at room temperature. Adding 6% Ag to Zr−20Ti alloy enhances the passivity breakdown potential and the self-corrosion potential, but hardly affects the corrosion current density and the impedance modulus. 6% Ag in Zr−40Ti alloy distinctly increases pitting corrosion resistance, which is attributed the formation of thick, dense and stable passive film under the joint action of titanium and silver. In comparison with cp Ti, Zr−40Ti−6Ag alloy possesses the same good corrosion resistance in the rigorous oral environment as well as the superior mechanical properties. - Highlights: • The quenched Zr20Ti and Zr40Ti obtain acicular martensite microstructure. • Zr20Ti and Zr40Ti possess high hardness, strength and strain to fracture. • Increasing Ti content decreases corrosion current density. • Adding Ag enhances passivation breakdown potentials of Zr20Ti and Zr40Ti. • Zr40Ti6Ag has optimum mechanical properties and pitting corrosion resistance.

  1. Computational Design of Creep-Resistant Alloys and Experimental Validation in Ferritic Superalloys

    Energy Technology Data Exchange (ETDEWEB)

    Liaw, Peter

    2014-12-31

    A new class of ferritic superalloys containing B2-type zones inside parent L21-type precipitates in a disordered solid-solution matrix, also known as a hierarchical-precipitate strengthened ferritic alloy (HPSFA), has been developed for high-temperature structural applications in fossil-energy power plants. These alloys were designed by the addition of the Ti element into a previously-studied NiAl-strengthened ferritic alloy (denoted as FBB8 in this study). In the present research, systematic investigations, including advanced experimental techniques, first-principles calculations, and numerical simulations, have been integrated and conducted to characterize the complex microstructures and excellent creep resistance of HPSFAs. The experimental techniques include transmission-electron microscopy, scanningtransmission- electron microscopy, neutron diffraction, and atom-probe tomography, which provide detailed microstructural information of HPSFAs. Systematic tension/compression creep tests revealed that HPSFAs exhibit the superior creep resistance, compared with the FBB8 and conventional ferritic steels (i.e., the creep rates of HPSFAs are about 4 orders of magnitude slower than the FBB8 and conventional ferritic steels.) First-principles calculations include interfacial free energies, anti-phase boundary (APB) free energies, elastic constants, and impurity diffusivities in Fe. Combined with kinetic Monte- Carlo simulations of interdiffusion coefficients, and the integration of computational thermodynamics and kinetics, these calculations provide great understanding of thermodynamic and mechanical properties of HPSFAs. In addition to the systematic experimental approach and first-principles calculations, a series of numerical tools and algorithms, which assist in the optimization of creep properties of ferritic superalloys, are utilized and developed. These numerical simulation results are compared with the available experimental data and previous first

  2. Standard guide for estimating the atmospheric corrosion resistance of low-alloy steels

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    2004-01-01

    1.1 This guide presents two methods for estimating the atmospheric corrosion resistance of low-alloy weathering steels, such as those described in Specifications A242/A242M, A588/A588M, A606 Type 4, A709/A709M grades 50W, HPS 70W, and 100W, A852/A852M, and A871/A871M. One method gives an estimate of the long-term thickness loss of a steel at a specific site based on results of short-term tests. The other gives an estimate of relative corrosion resistance based on chemical composition. 1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

  3. An ab initio investigation of how residual resistivity can decrease when an alloy is deformed

    Science.gov (United States)

    Lowitzer, S.; Ködderitzsch, D.; Ebert, H.; Tulip, P. R.; Marmodoro, A.; Staunton, J. B.

    2010-11-01

    For a class of transition metal materials residual resistivity is observed to decrease when the materials are deformed and short-range order is removed. We investigate this counter-intuitive behavior with an ab initio theoretical study of the residual resistivity of several late transition metal-rich disordered alloys. The calculations are performed using the Korringa-Kohn-Rostoker (KKR) method applied to the Kubo-Greenwood formalism. The electronic effects arising from short-range ordering and clustering within the disorder are described using the non-local coherent-potential approximation (NL-CPA). We find a simple, general explanation of this K-state-like effect in terms of changes to the amplitude for d-electron hopping between majority late transition metal nearest-neighbor atoms at the Fermi energy.

  4. Influence Of Lubricants On Wear Resistance Of Aluminum Alloy Strips Series 2XXX

    Directory of Open Access Journals (Sweden)

    Żaba K.

    2015-09-01

    Full Text Available The article presents a properly planned and designed tests of the abrasive wear resistance 2024 aluminum alloy strips under friction conditions involving various lubricants. Test were focused on the selection of the best lubricant for use in industrial environment, especially for sheet metal forming. Three lubricants of the Orlen Oil Company and one used in the sheet metal forming industry, were selected for tests. Tests without the use of lubricant were performed for a comparison. The tester T-05 was used for testing resistance to wear. As the counter samples were used tool steel - NC6 and steel for hot working - WCL, which are typical materials used for tools for pressing. The results are presented in the form of the force friction, abrasion depth, weight loss and coefficient of friction depending on the lubricant used and the type of counter samples. The results allowed for predicting set lubricant-material for tools which can be applied to sheet metal made of aluminum alloy 2024.

  5. Evaluation of the stress corrosion cracking resistance of several high strength low alloy steels

    Science.gov (United States)

    Humphries, T. S.; Nelson, E. E.

    1980-01-01

    The stress corrosion cracking resistance was studied for high strength alloy steels 4130, 4340, for H-11 at selected strength levels, and for D6AC and HY140 at a single strength. Round tensile and C-ring type specimens were stressed up to 100 percent of their yield strengths and exposed to alternate immersion in salt water, salt spray, the atmosphere at Marshall Space Flight Center, and the seacoast at Kennedy Space Center. Under the test conditions, 4130 and 4340 steels heat treated to a tensile strength of 1240 MPa (180 ksi), H-11 and D6AC heat treated to a tensile strength of 1450 MPa (210 ksi), and HY140 (1020 MPa, 148 ksi) are resistant to stress corrosion cracking because failures were not encountered at stress levels up to 75 percent of their yield strengths. A maximum exposure period of one month for alternate immersion in salt water or salt spray and three months for seacoast is indicated for alloy steel to avoid false indications of stress corrosion cracking because of failure resulting from severe pitting.

  6. Nanocomposite films of cobalt-containing polyacrylonitrile as a basis of gas-sensitive material for resistive type sensors

    Science.gov (United States)

    Bednaya, T. A.; Konovalenko, S. P.

    2017-05-01

    The structure of the metal-carbon nanocomposite based on cobalt-containing polyacrylonitrile (PAN) is studied. The morphology of a surface with the theory of selforganization was analysed. The elemental composition, chemical and electronic states of the elements composing the material films are determined by the X-ray photoelectron spectroscopy (XPS) method. The X-ray diffraction (XRD) method shows that the obtained materials contain crystalline inclusions of CoO, Co3O4 and CoO (OH) in the organic matrix of PAN. Gas-sensitive characteristics of the obtained films.

  7. Corrosion resistance after mechanical deformation of the Ti30Ta experimental alloy for using in biomedical applications

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Kerolene Barboza da; Konatu, Reginaldo Toshihiro; Oliveira, Liliane Lelis de; Nakazato, Roberto Zenhei; Claro, Ana Paula Rosifini Alves, E-mail: rosifini@feg.unesp.br [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Guaratinguetá, SP (Brazil). Departamento de Engenharia de Materiais

    2017-10-15

    In this study the corrosion resistance of Ti30Ta experimental alloy was evaluated when submitted to different deformation rates. Alloys were processed in arc melting, furnace, forged and treated. The samples were machined in accordance with ASTME9-09 standard to carry out compression tests. The influence of deformation was evaluated by optical microscopy and XRD, and Electrochemical parameters were analyzed in the most severe condition of deformation (22%). Corrosion resistance exhibited the same behavior for two conditions, 22% and without deformation. (author)

  8. Effects of sealing treatment on corrosion resistance and degradation behavior of micro-arc oxidized magnesium alloy wires

    Science.gov (United States)

    Chu, C. L.; Han, X.; Xue, F.; Bai, J.; Chu, P. K.

    2013-04-01

    The effects of three different sealing treatments on micro-arc oxidized (MAO) medical magnesium alloy wires using boiling water, zirconia sol-gel, and organic gelatin-hydroxyapatite (HA) coatings on the surface morphology, corrosion resistance, and degradation behavior in simulated body fluid (SBF) and simulated intestinal fluid (SIF) are investigated. The treatments involving boiling water or gelatin-HA coating can effectively seal the discharge channels making the surface pores less and smaller. The treatments also improve the corrosion resistance of the MAO magnesium alloy wires, especially the samples with the gelatin-HA coatings which also exhibit reduced degradation in both simulated physiological environments.

  9. Effect of temperature on the corrosion resistance and pitting behaviour of Alloy 31 in LiBr solutions

    Energy Technology Data Exchange (ETDEWEB)

    Blasco-Tamarit, E.; Igual-Munoz, A. [Departamento de Ingenieria Quimica y Nuclear, E.T.S.I. Industriales, Universidad Politecnica de Valencia, P.O. Box 22012, E-46071 Valencia (Spain); Anton, J. Garcia [Departamento de Ingenieria Quimica y Nuclear, E.T.S.I. Industriales, Universidad Politecnica de Valencia, P.O. Box 22012, E-46071 Valencia (Spain)], E-mail: jgarciaa@iqn.upv.es; Garcia-Garcia, D. [Departamento de Ingenieria Quimica y Nuclear, E.T.S.I. Industriales, Universidad Politecnica de Valencia, P.O. Box 22012, E-46071 Valencia (Spain)

    2008-07-15

    The corrosion resistance and pitting behaviour of Alloy 31, a high-alloyed austenitic stainless steel (UNS N08031), is studied in two heavy brine LiBr solutions (850 g/l) with and without corrosion inhibitor (lithium chromate) at different temperatures (25 deg. C, 50 deg. C, 75 deg. C and 100 deg. C) using electrochemical techniques. Cyclic potentiodynamic curves indicate that UNS N08031 is less pitting corrosion resistant and it reduces its repassivation properties as temperature increases. Comparison between the results obtained in LiBr solutions with and without inhibitor suggested a decrease in the inhibitor efficiency of lithium chromate at high temperatures.

  10. Prediction of liquid metal alloy radiant properties from measurements of the Hall coefficient and the direct current resistivity

    International Nuclear Information System (INIS)

    Havstad, M.A.; Qiu, T.

    1995-04-01

    The thermal radiative properties of high temperature solid and liquid metal alloys are particularly useful to research and development efforts in laser cladding and machining, electron beam welding and laser isotope separation. However the cost, complexity, and difficulty of measuring these properties have forced the use of crude estimates from the Hagen-Rubens relation, the Drude relations, or extrapolation from low temperature or otherwise flawed data (e.g., oxidized). The authors have found in this work that published values for the Hall coefficient and the electrical resistivity of liquid metal alloys can provide useful estimates of the reflectance and emittance of some groups of binary liquid metal and high temperature solid alloys. The estimation method computes the Drude free electron parameters, and thence the optical constants and the radiant properties from the dependence of the Hall coefficient and direct current resistivity on alloy composition (the Hall coefficient gives the free electron density and the resistivity gives the average time between collisions). They find that predictions of the radiant properties of molten cerium-copper alloy, which use the measured variations in the Hall coefficient and resistivity (both highly nonlinear) as a function of alloy fraction (rather than linear combinations of the values of the pure elements) yield a good comparison to published measurements of the variation of the normal spectral emittance (a different but also nonlinear function) of cerium-copper alloy at the single wavelength available for comparison, 0.645 μm. The success of the approach in the visible range is particularly notable because one expects a Drude based approach to improve with increasing wavelength from the visible into the infrared. Details of the estimation method, the comparison between the calculation and the measured emittance, and a discussion of what groups of elements may also provide agreement is given

  11. RELATION BETWEEN NMR PROPERTIES AND ELECTRICAL-RESISTIVITY IN LI-GE, LI-SN AND LI-PB LIQUID ALLOYS

    NARCIS (Netherlands)

    XU, R; VANDERLUGT, W

    1994-01-01

    Recent measurements of the electrical resistivity of liquid Li-Ge alloys enable us to check relations between NMR properties and resistivity in non-metallic alloys derived by Warren in 1971. It is shown that the predicted linear relationships hold, but that the proportionality between the square

  12. Mechanic resistance and elongation of Fe-24%at.Al base intermetallic alloys; Resistencia mecanica e alongamento de ligas intermetalicas a base de Fe-24%at.Al

    Energy Technology Data Exchange (ETDEWEB)

    Couto, Antonio A.; Paola, Jean C.C. de; Ferreira, Paulo I. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    1992-12-31

    The iron and aluminum based intermetallic alloys presents good mechanic resistance until 600 deg C and excellent corrosion resistance. However, the low ductility were limited its application. This work shows the study of the effects of Chromium addition and heat treatment conditions on room temperature tensile properties of the hot-rolled Iron based alloys are also focused. 6 figs., 2 tabs., 29 refs.

  13. Radiation enhanced copper clustering processes in Fe-Cu alloys during electron and ion irradiations as measured by electrical resistivity

    International Nuclear Information System (INIS)

    Ishino, S.; Chimi, Y.; Bagiyono; Tobita, T.; Ishikawa, N.; Suzuki, M.; Iwase, A.

    2003-01-01

    To study the mechanism of radiation-enhanced clustering of copper atoms in Fe-Cu alloys, in situ electrical resistivity measurements are performed during irradiation with 100 MeV carbon ions and with 2 MeV electrons at 300 K. Two kinds of highly pure Fe-Cu alloys with Cu content of 0.02 and 0.6 wt% are used. The results are summarized as follows: - Although there is a steep initial resistivity increase below about 10 μdpa, the resistivity steadily decreases after this initial transient in Fe-0.6wt%Cu alloy, while in Fe-0.02wt%Cu alloy, the resistivity either decreases slowly or stays almost constant. The rate of change in resistivity depends on copper concentration. - The rate of change in resistivity per dpa is larger for electron irradiation than for ion irradiation. - Change in dose rate from 10 -8 to 10 -9 dpa/s slightly enhances the rate of resistivity change per dpa. The decrease in resistivity with dose is considered to be due to clustering or precipitation of copper atoms. The initial abrupt increase in resistivity is too large to be accounted for by initial introduction of point defects before copper clustering. Tentatively the phenomenon is explained as due to the formation of embryos of copper precipitates with a large strain field around them. Quantitative evaluation of the results using resistivity contribution of a unit concentration of Frenkel pairs and that of copper atoms gives an important conclusion that more than one copper atom are removed from solid solution by one Frenkel pair. The clustering efficiency is surprisingly high in the present case compared with the ordinary radiation-induced or radiation-enhanced precipitation processes

  14. A peptide-based biological coating for enhanced corrosion resistance of titanium alloy biomaterials in chloride-containing fluids.

    Science.gov (United States)

    Muruve, Noah; Feng, Yuanchao; Platnich, Jaye; Hassett, Daniel; Irvin, Randall; Muruve, Daniel; Cheng, Frank

    2017-03-01

    Titanium alloys are common materials in the manufacturing of dental and orthopedic implants. Although these materials exhibit excellent biocompatibility, corrosion in response to biological fluids can impact prosthesis performance and longevity. In this work, a PEGylated metal binding peptide (D-K122-4-PEG), derived from bacteria Pseudomonas aeruginosa, was applied on a titanium (Ti) alloy, and the corrosion resistance of the coated alloy specimen was investigated in simulated chloride-containing physiological fluids by electrochemical impedance spectroscopy and micro-electrochemical measurements, surface characterization, and biocompatibility testing. Compared to uncoated specimen, the D-K122-4-PEG-coated Ti alloy demonstrates decreased corrosion current density without affecting the natural passivity. Morphological analysis using atomic force microscopy and scanning electron microscopy confirms a reduction in surface roughness of the coated specimens in the fluids. The D-K122-4-PEG does not affect the binding of HEK-293T cells to the surface of unpolished Ti alloy, nor does it increase the leukocyte activation properties of the metal. D-K122-4-PEG represents a promising coating to enhance the corrosion resistance of Ti alloys in physiological fluids, while maintaining an excellent biocompatibility.

  15. Synthesis and characterization of cobalt oxide and titanium mixtures using mechanical alloying and its response to oxygen reduction; Sintesis y caracterizacion de mezclas de oxidos de cobalto y titanio por aleado mecanico y su respuesta para la reduccion de oxigeno

    Energy Technology Data Exchange (ETDEWEB)

    Basurto S, R.; Bonifacio-Martinez, J.; Fernandez, S.M [Instituto Nacional de Investigaciones Nucleares, Ocoyoacac, Estado de Mexico (Mexico)]. E-mail: rafael.basurto@inin.gob.mx

    2009-09-15

    The synthesis of Co{sub 3}O{sub 4} and CoTiO{sub 3} oxides was conducted using mechanical alloying and combustion. Co{sub 3}O{sub 4} used was obtained using a SPEX ball mill with cobalt nitrate, Co(NO{sub 3})36H{sub 2}O plus urea, CH{sub 4}N{sub 2}O, in a molar ratio of 1:1 and a ball weight ratio of 1:4 with grinding times of 2.5 hours in an argon atmosphere. The material obtained after alloying underwent combustion at 400 degrees Celsius and 500 degrees Celsius, obtaining oxides of mixed cobalt valence. This material was mixed with TiO{sub 2} with a weight ratio of 1:1 and was mechanically alloyed with a ball weight ratio of 1:8; grinding was performed for 2.5 hours in argon atmosphere and it underwent combustion at 800 degrees Celsius. Characterization was performed using x-ray diffraction, low-vacuum sweep electron microscopy and EDS. The electrochemical performance was obtained in a galvanostat-potentiostat (Princenton Applied Research modelo 273). Both materials present electrocatalytic activity for oxygen reduction reaction in alkaline medium. [Spanish] La sintesis de los oxidos: Co{sub 3}O{sub 4} y CoTiO3 se realizo por la tecnica de aleado mecanico y combustion. El Co{sub 3}O{sub 4} utilizado, se obtuvo por con un molino de bolas SPEX, utilizando nitrato de cobalto, Co(NO{sub 3})36H{sub 2}O mas urea, CH{sub 4}N{sub 2}O, en una relacion molar 1:1.y una relacion en peso de bolas de 1:4 con tiempos de molienda de 2.5 horas, en atmosfera de argon, al termino del aleado el material obtenido se llevo a combustion a 400 grados centigrados y 500 grados centigrados, obteniendose el oxido de valencia mixta de cobalto. Este material se mezclo con TiO{sub 2}, en una relacion en peso de 1:1 y se aleo mecanicamente, con una relacion en peso de bolas de 1:8, por 2.5 horas de molienda en atmosfera de argon y llevandolo a combustion a 800 grados centigrados. La caracterizacion se hizo por: Difraccion de Rayos X, Microscopia Electronica de Barrido de Bajo Vacio y EDS El

  16. Alloying behaviour of electroplated Ag film with its underlying Pd/Ti film stack for low resistivity interconnect metallization

    Energy Technology Data Exchange (ETDEWEB)

    Ezawa, Hirokazu, E-mail: hirokazu.ezawa@toshiba.co.jp [Toshiba Corporation, Semiconductor and Storage Products Company (Japan); The Graduate School of Information, Production and Systems, Waseda University (Japan); Miyata, Masahiro [Toshiba Corporation, Semiconductor and Storage Products Company (Japan); Tatsumi, Kohei [The Graduate School of Information, Production and Systems, Waseda University (Japan)

    2014-02-25

    Highlights: • Alloying behavior of Ag/Pd/Ti film stack was studied by annealing at 400-800 °C. • The Ag film resistivity decreased with increasing annealing temperature. • Formation of the Pd-Ti intermetallics was found to be dominant over Ag-Pd alloying. • The excess Ti was consumed to form Ti oxides, which inhibited Ti alloying with Ag. -- Abstract: In this paper, viability of electroplated Ag film into device application was studied. Alloying behavior of the Ag film with its underlying Pd(50 nm)/Ti(100 nm) film stack was investigated with respect to heat treatment at different temperatures from 400 °C to 800 °C in an argon ambient. After annealing at 400 °C, the electrical resistivity of the Ag film increased due to Pd alloying with Ag. Formation of Pd–Ti intermetallic phases became dominant over Ag–Pd alloying with increasing annealing temperature, leading to the resistivity decrease of the Ag film. The resistivity of the 800 °C annealed Ag film approached that of its as-plated Ag film. The excess Ti atoms which were not consumed to form the intermetallic phases with the Pd atoms migrated to the Ag film surface to form Ti oxides along the Ag grain boundaries on the topmost film surface. The Ag/Pd/Ti film stack has been confirmed to maintain the resistivity of the Ag film at as-plated low levels after high temperature annealing. This paper also discusses process integration issues to enable the Ag metallization process for future scaled and three dimensionally chip stacked devices.

  17. Alloying behaviour of electroplated Ag film with its underlying Pd/Ti film stack for low resistivity interconnect metallization

    International Nuclear Information System (INIS)

    Ezawa, Hirokazu; Miyata, Masahiro; Tatsumi, Kohei

    2014-01-01

    Highlights: • Alloying behavior of Ag/Pd/Ti film stack was studied by annealing at 400-800 °C. • The Ag film resistivity decreased with increasing annealing temperature. • Formation of the Pd-Ti intermetallics was found to be dominant over Ag-Pd alloying. • The excess Ti was consumed to form Ti oxides, which inhibited Ti alloying with Ag. -- Abstract: In this paper, viability of electroplated Ag film into device application was studied. Alloying behavior of the Ag film with its underlying Pd(50 nm)/Ti(100 nm) film stack was investigated with respect to heat treatment at different temperatures from 400 °C to 800 °C in an argon ambient. After annealing at 400 °C, the electrical resistivity of the Ag film increased due to Pd alloying with Ag. Formation of Pd–Ti intermetallic phases became dominant over Ag–Pd alloying with increasing annealing temperature, leading to the resistivity decrease of the Ag film. The resistivity of the 800 °C annealed Ag film approached that of its as-plated Ag film. The excess Ti atoms which were not consumed to form the intermetallic phases with the Pd atoms migrated to the Ag film surface to form Ti oxides along the Ag grain boundaries on the topmost film surface. The Ag/Pd/Ti film stack has been confirmed to maintain the resistivity of the Ag film at as-plated low levels after high temperature annealing. This paper also discusses process integration issues to enable the Ag metallization process for future scaled and three dimensionally chip stacked devices

  18. Influence of polyetheretherketone coatings on the Ti-13Nb-13Zr titanium alloy's bio-tribological properties and corrosion resistance.

    Science.gov (United States)

    Sak, Anita; Moskalewicz, Tomasz; Zimowski, Sławomir; Cieniek, Łukasz; Dubiel, Beata; Radziszewska, Agnieszka; Kot, Marcin; Łukaszczyk, Alicja

    2016-06-01

    Polyetheretherketone (PEEK) coatings of 70-90μm thick were electrophoretically deposited from a suspension of PEEK powder in ethanol on near-β Ti-13Nb-13Zr titanium alloy. In order to produce good quality coatings, the composition of the suspension (pH) and optimized deposition parameters (applied voltage and time) were experimentally selected. The as-deposited coatings exhibited the uniform distribution of PEEK powders on the substrate. The subsequent annealing at a temperature above the PEEK melting point enabled homogeneous, semi-crystalline coatings with spherulitic morphology to be produced. A micro-scratch test showed that the coatings exhibited very good adhesion to the titanium alloy substrate. Coating delamination was not observed even up to a maximal load of 30N. The PEEK coatings significantly improved the tribological properties of the Ti-13Nb-13Zr alloy. The coefficient of friction was reduced from 0.55 for an uncoated alloy to 0.40 and 0.12 for a coated alloy in a dry sliding and sliding in Ringer's solution, respectively. The PEEK coatings exhibited excellent wear resistance in both contact conditions. Their wear rate was more than 200 times smaller compared with the wear rate of the uncoated Ti-13Nb-13Zr alloy. The obtained results indicate that electrophoretically deposited PEEK coatings on the near-β titanium alloy exhibit very useful properties for their prospective tribological applications in medicine. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Surface Characterization, Corrosion Resistance and in Vitro Biocompatibility of a New Ti-Hf-Mo-Sn Alloy

    Science.gov (United States)

    Ion, Raluca; Drob, Silviu Iulian; Ijaz, Muhammad Farzik; Vasilescu, Cora; Osiceanu, Petre; Gordin, Doina-Margareta; Cimpean, Anisoara; Gloriant, Thierry

    2016-01-01

    A new superelastic Ti-23Hf-3Mo-4Sn biomedical alloy displaying a particularly large recovery strain was synthesized and characterized in this study. Its native passive film is very thick (18 nm) and contains very protective TiO2, Ti2O3, HfO2, MoO2, and SnO2 oxides (XPS analysis). This alloy revealed nobler electrochemical behavior, more favorable values of the corrosion parameters and open circuit potentials in simulated body fluid in comparison with commercially pure titanium (CP-Ti) and Ti-6Al-4V alloy taken as reference biomaterials in this study. This is due to the favorable influence of the alloying elements Hf, Sn, Mo, which enhance the protective properties of the native passive film on alloy surface. Impedance spectra showed a passive film with two layers, an inner, capacitive, barrier, dense layer and an outer, less insulating, porous layer that confer both high corrosion resistance and bioactivity to the alloy. In vitro tests were carried out in order to evaluate the response of Human Umbilical Vein Endothelial Cells (HUVECs) to Ti-23Hf-3Mo-4Sn alloy in terms of cell viability, cell proliferation, phenotypic marker expression and nitric oxide release. The results indicate a similar level of cytocompatibility with HUVEC cells cultured on Ti-23Hf-3Mo-4Sn substrate and those cultured on the conventional CP-Ti and Ti-6Al-4V metallic materials. PMID:28773939

  20. Hexagonal Boron Nitride Impregnated Silane Composite Coating for Corrosion Resistance of Magnesium Alloys for Temporary Bioimplant Applications

    Directory of Open Access Journals (Sweden)

    Saad Al-Saadi

    2017-11-01

    Full Text Available Magnesium and its alloys are attractive potential materials for construction of biodegradable temporary implant devices. However, their rapid degradation in human body fluid before the desired service life is reached necessitate the application of suitable coatings. To this end, WZ21 magnesium alloy surface was modified by hexagonal boron nitride (hBN-impregnated silane coating. The coating was chemically characterised by Raman spectroscopy. Potentiodynamic polarisation and electrochemical impedance spectroscopy (EIS of the coated alloy in Hanks’ solution showed a five-fold improvement in the corrosion resistance of the alloy due to the composite coating. Post-corrosion analyses corroborated the electrochemical data and provided a mechanistic insight of the improvement provided by the composite coating.

  1. The evaluation of dynamic cracking resistance of chosen casting alloys in the aspect of the impact bending test

    Directory of Open Access Journals (Sweden)

    J.Sadowski

    2008-10-01

    Full Text Available The increase of quality and durability of produced casting alloys can be evaluated on the base of material tests performed on a high level. One of such modern test methods are tests of the dynamic damage process of materials and the evaluation on the base of obtained courses F(f, F(t of parameters of dynamic cracking resistance KId, JId, performed with the usage of instrumented Charpy pendulums. In the paper there was presented the evaluation of dynamic cracking resistance parameters of casting alloys such as: AK12 aluminum alloy, L20G cast steel and spheroid cast iron. The methodology of the evaluation of that parameters was described and their change as well, for the AK12 alloy with the cold work different level, L20G cast steel cooled from different temperatures in the range +20oC -60oC, and for the spheroid cast iron in different stages of treatment i.e. raw state, after normalization, spheroid annealing and graphitizing annealing.Obtained parameters of dynamic cracking resistance KId, JId of tested casting alloys enabled to define the critical value of the ad defect that can be tolerated by tested castings in different work conditions with impact loadings.

  2. Effect of Contact Temperature Rise During Sliding on the Wear Resistance of TiNi Shape Memory Alloys

    Directory of Open Access Journals (Sweden)

    S.K. Roy Chowdhury

    2013-03-01

    Full Text Available The high wear resistance of TiNi shape memory alloys has generally been attributed to its pseudoelastic nature. In the present work the hardening effect due to its phase transformation from martensite to austenite due to frictional heating during sliding has been considered. Based on existing constitutive models that represent the experimental results of TiNi shape memory alloys a theoretical model of the dependence of wear-resistance on the contact temperature rise has been developed. The analysis was further extended to include the operating and surface roughness parameters. The model essentially indicates that for these alloys wear decreases with the rise in contact temperature over a wide range of load, speed and surface roughness combination during sliding. This means that the wear resistance of these alloys results from the very cause that is normally responsible for the increased wear and seizure of common engineering materials. Preliminary wear tests were carried out with TiNi alloys at varying ambient temperature and varying load-speed combinations and the results agree well with the theoretical predictions.

  3. Enhanced corrosion resistance and biocompatibility of AZ31 Mg alloy using PCL/ZnO NPs via electrospinning

    International Nuclear Information System (INIS)

    Kim, Jinwoo; Mousa, Hamouda M.; Park, Chan Hee; Kim, Cheol Sang

    2017-01-01

    Highlights: • PCL/ZnO composite coating layer by electrospinning techniques showed the nano-scaled and porous surface structure. • Addition of zinc oxide NPs in the PCL fibers led to enhanced coating adhesion and corrosion resistance. • The composite coated surfaces on Mg substrates improved cell attachment and proliferation. - Abstract: In the efforts to improve corrosion resistance and biocompatibility of magnesium alloys, polycarprolactone (PCL) and zinc oxide nanoparticles (ZnO NPs) composite coatings were applied onto AZ31 Mg alloys via electrospinning technique in this study. The PCL/ZnO composite coatings on Mg alloys were characterized by using FE-SEM, EDX, XPS, and FT-IR. Moreover, coating adhesion test, electrochemical corrosion test, and biocompatibility test in vitro were performed to measure coating performance. Our results revealed that the increase in the content of ZnO NPs in the composite coatings not only improved the coating adhesion of composite coatings on Mg alloys, but also increased the corrosion resistance. Furthermore, the biocompatibility of MC3T3-E1 osteoblasts of the PCL/ZnO composite coated samples was superior to the biocompatibility of the bare samples. Such data suggest that applying PCL/ZnO composite coating to the magnesium alloys has suitable potential in biomedical applications.

  4. Investigation on the of effect of self assembling molecules on the corrosion resistance of the 1050 aluminium alloy

    International Nuclear Information System (INIS)

    Szurkalo, Margarida

    2009-01-01

    Surface treatments are widely used to increase the corrosion resistance of metallic materials. Specifically for aluminum and aluminum alloys, treatment with hexavalent chromium is one of the most used, due to its efficiency and ease of application. However, because of environmental restrictions and the high cost involved in the treatments of waste generated in this process, alternative methods for its replacement are necessary. In this context, this study investigated the effect of the surface treatment with self-assembling molecules (SAM) based on phosphonate compounds on the corrosion of the 1050 aluminum alloy. The conditions adopted for the SAM treatment were determined by conductivity and contact angle measurements, besides electrochemical experiments. Electrochemical techniques, specifically: measurement of the open circuit potential (OCP) variation with time, electrochemical impedance spectroscopy (EIS) and potentiodynamic polarization curves were used to evaluate the corrosion resistance of the 1050 aluminum alloy exposed to SAM treatment The experimental impedance diagrams were interpreted using equivalent electrical circuit models that simulate film that is formed on the alloy surface. The results of the samples treated with SAM were compared with those of samples either without any treatment or treated with chromatizing conversion coating with Cr(VI) and showed that the first treatment significantly increased the corrosion resistance of the aluminum alloy and approached that of chromatizing with Cr(VI) process. (author)

  5. Cu-Containing Fe-Ni Corrosion-Resistant Alloys Designed by a Cluster-Based Stable Solid Solution Model

    Science.gov (United States)

    Li, Baozeng; Wang, Qing; Wang, Yingmin; Li, Chunyan; Qiang, Jianbing; Ji, Chunjun; Dong, Chuang

    2012-02-01

    Copper is a good corrosion resisting element, but due to its immiscibility with Fe, it is only used as a minor-alloying element in stainless steels. In this work, we introduced a double-cluster structure model [CuNi12][NiFe12] m for stable solid solutions in Cu-containing Fe-Ni corrosion-resistant invar alloys. Our model takes into account all of the enthalpies between the element pairs by assuming Fe-Ni and Ni-Cu nearest neighbors and by avoiding Fe-Cu ones, so that the ideally stabilized structures are described by mixing two cuboctahedral clusters in the fcc lattice, NiFe12 and CuNi12. Two alloy series were designed by varying the relative proportions of the two clusters and the Cu contents. It was proved that the alloys with Cu contents below those prescribed by this model could easily be solutionized and water-quenched to a monolithic fcc solid solution, and resultant alloys possessed good corrosion-resisting properties in 3.5 wt pct NaCl solution.

  6. Enhanced corrosion resistance and biocompatibility of AZ31 Mg alloy using PCL/ZnO NPs via electrospinning

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jinwoo [Department of Bionanosystem Engineering, Graduate School, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Mousa, Hamouda M. [Department of Bionanosystem Engineering, Graduate School, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Department of Engineering Materials and Mechanical Design, Faculty of Engineering, South Valley University, Qena 83523 (Egypt); Park, Chan Hee, E-mail: biochan@jbnu.ac.kr [Department of Bionanosystem Engineering, Graduate School, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Division of Mechanical Design Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of); Kim, Cheol Sang, E-mail: chskim@jbnu.ac.kr [Department of Bionanosystem Engineering, Graduate School, Chonbuk National University, Jeonju 561-756 (Korea, Republic of); Division of Mechanical Design Engineering, Chonbuk National University, Jeonju, Jeonbuk 561-756 (Korea, Republic of)

    2017-02-28

    Highlights: • PCL/ZnO composite coating layer by electrospinning techniques showed the nano-scaled and porous surface structure. • Addition of zinc oxide NPs in the PCL fibers led to enhanced coating adhesion and corrosion resistance. • The composite coated surfaces on Mg substrates improved cell attachment and proliferation. - Abstract: In the efforts to improve corrosion resistance and biocompatibility of magnesium alloys, polycarprolactone (PCL) and zinc oxide nanoparticles (ZnO NPs) composite coatings were applied onto AZ31 Mg alloys via electrospinning technique in this study. The PCL/ZnO composite coatings on Mg alloys were characterized by using FE-SEM, EDX, XPS, and FT-IR. Moreover, coating adhesion test, electrochemical corrosion test, and biocompatibility test in vitro were performed to measure coating performance. Our results revealed that the increase in the content of ZnO NPs in the composite coatings not only improved the coating adhesion of composite coatings on Mg alloys, but also increased the corrosion resistance. Furthermore, the biocompatibility of MC3T3-E1 osteoblasts of the PCL/ZnO composite coated samples was superior to the biocompatibility of the bare samples. Such data suggest that applying PCL/ZnO composite coating to the magnesium alloys has suitable potential in biomedical applications.

  7. Shape memory alloy resistance behaviour at high altitude for feedback control

    Science.gov (United States)

    Ng, W. T.; Sedan, M. F.; Abdullah, E. J.; Azrad, S.; Harithuddin, A. S. M.

    2017-12-01

    Many recent aerospace technologies are using smart actuators to reduce the system's complexity and increase its reliability. One such actuator is shape memory alloy (SMA) actuator, which is lightweight, produces high force and large deflection. However, some disadvantages in using SMA actuators have been identified and they include nonlinear response of the strain to input current, hysteresis characteristic that results in inaccurate control and less than optimum system performance, high operating temperatures, slow response and also high requirement of electrical power to obtain the desired actuation forces. It is still unknown if the SMA actuators can perform effectively at high altitude with low surrounding temperature. The work presented here covers the preliminary process of verifying the feasibility of using resistance as feedback control at high altitude for aerospace applications. Temperature and resistance of SMA actuator at high altitude is investigated by conducting an experiment onboard a high altitude balloon. The results from the high altitude experiment indicate that the resistance or voltage drop of the SMA wire is not significantly affected by the low surrounding temperature at high altitude as compared to the temperature of SMA. Resistance feedback control for SMA actuators may be suitable for aerospace applications.

  8. Dual ions implantation of zirconium and nitrogen into magnesium alloys for enhanced corrosion resistance, antimicrobial activity and biocompatibility.

    Science.gov (United States)

    Cheng, Mengqi; Qiao, Yuqin; Wang, Qi; Qin, Hui; Zhang, Xianlong; Liu, Xuanyong

    2016-12-01

    Biodegradable magnesium-based alloys have shown great potential for medical applications due to their superior biological performances and mechanical properties. However, on one hand, some side effects including inferior biocompatibility, a local high-alkaline environment and gas cavities caused by a rapid corrosion rate, hinder their clinical application. On the other hand, it is also necessary to endow Mg alloys with antibacterial properties, which are crucial for clinic orthopedic applications. In this study, Zr and N ions are simultaneously implanted into AZ91 Mg alloys by plasma immersion ion implantation (PIII). A modified layer with a thickness of approximately 80nm is formed on the surface of AZ91 Mg alloys, and the hydrophobicity and roughness of these AZ91 Mg alloys obviously increase after Zr and N implantation. The in vitro evaluations including corrosion resistance tests, antimicrobial tests and cytocompatibility and alkaline phosphatase (ALP) activity tests, revealed that the dual ions implantation of Zr and N not only enhanced the corrosion resistance of the AZ91 Mg alloy but also provided better antimicrobial properties in vitro. Furthermore, the formation of biocompatible metal nitrides and metal oxides layer in the near surface of the Zr-N-implanted AZ91 Mg alloy provided a favorable implantation surface for cell adhesion and growth, which in return further promoted the bone formation in vivo. These promising results suggest that the Zr-N-implanted AZ91 Mg alloy shows potential for future application in the orthopedic field. Copyright © 2016 Elsevier B.V. All rights reserved.

  9. Mechanical, In Vitro Corrosion Resistance and Biological Compatibility of Cast and Annealed Ti25Nb10Zr Alloy

    Directory of Open Access Journals (Sweden)

    Cosmin M. Cotrut

    2017-03-01

    Full Text Available Compared to other alloys, Ti6Al4V is the most used in medicine. In recent years, concerns regarding the toxicity of Al and V elements found in the composition of Ti6Al4V have drawn the attention of the scientific community, due to the release of Al or V ions after long term exposure to human body fluids which can lead to a negative response of the human host. Based on this, the aim of the paper was to manufacture a Ti25Nb10Zr alloy consisting of biocompatible elements which can replace Ti6Al4V usage in medical applications. In order to prove that this alloy possessed improved properties, the mechanical, wear and corrosion resistance, wettability, and cell viability were performed in comparison with those of the Ti6Al4V alloy. The corrosion behavior of this new alloy in simulated body fluid (SBF and Hank solutions is superior to that of Ti6Al4V. The cast Ti25Nb10Zr alloy has a good tribological performance in SBF, while annealed Ti25Nb10Zr alloy is better in Hank solution. Cell viability and proliferation assay after five days indicated that Ti25Nb10Zr presented a good viability and proliferation with values of approximately 7% and 10% higher, respectively, than the ones registered for pure Ti. When compared with Ti6Al4V, the obtained results for Ti25Nb10Zr indicated smaller values with 20% in the case of both tests. Overall, it can be concluded that cell proliferation and viability tests indicated that the biocompatibility of the Ti25Nb10Zr alloy is as good as pure Ti and Ti6Al4V alloy.

  10. Creep resistant high temperature martensitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Hawk, Jeffrey A.; Jablonski, Paul D.; Cowen, Christopher J.

    2015-11-13

    The disclosure provides a creep resistant alloy having an overall composition comprised of iron, chromium, molybdenum, carbon, manganese, silicon, nickel, vanadium, niobium, nitrogen, tungsten, cobalt, tantalum, boron, and potentially additional elements. In an embodiment, the creep resistant alloy has a molybdenum equivalent Mo(eq) from 1.475 to 1.700 wt. % and a quantity (C+N) from 0.145 to 0.205. The overall composition ameliorates sources of microstructural instability such as coarsening of M.sub.23C.sub.6 carbides and MX precipitates, and mitigates or eliminates Laves and Z-phase formation. A creep resistant martensitic steel may be fabricated by preparing a melt comprised of the overall composition followed by at least austenizing and tempering. The creep resistant alloy exhibits improved high-temperature creep strength in the temperature environment of around 650.degree. C.

  11. Creep resistant high temperature martensitic steel

    Energy Technology Data Exchange (ETDEWEB)

    Hawk, Jeffrey A.; Jablonski, Paul D.; Cowen, Christopher J.

    2017-01-31

    The disclosure provides a creep resistant alloy having an overall composition comprised of iron, chromium, molybdenum, carbon, manganese, silicon, nickel, vanadium, niobium, nitrogen, tungsten, cobalt, tantalum, boron, copper, and potentially additional elements. In an embodiment, the creep resistant alloy has a molybdenum equivalent Mo(eq) from 1.475 to 1.700 wt. % and a quantity (C+N) from 0.145 to 0.205. The overall composition ameliorates sources of microstructural instability such as coarsening of M.sub.23C.sub.6carbides and MX precipitates, and mitigates or eliminates Laves and Z-phase formation. A creep resistant martensitic steel may be fabricated by preparing a melt comprised of the overall composition followed by at least austenizing and tempering. The creep resistant alloy exhibits improved high-temperature creep strength in the temperature environment of around 650.degree. C.

  12. Zirconium alloys with small amounts of iron and copper or nickel show improved corrosion resistance in superheated steam

    Science.gov (United States)

    Greenberg, S.; Youngdahl, C. A.

    1967-01-01

    Heat treating various compositions of zirconium alloys improve their corrosion resistance to superheated steam at temperatures higher than 500 degrees C. This increases their potential as fuel cladding for superheated-steam nuclear-fueled reactors as well as in autoclaves operating at modest pressures.

  13. Computer Simulation and Experimental Validation on the Oxidation and Sulfate Corrosion Resistance of Novel Chromium Based High Temperature Alloys

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Shizhong

    2013-02-28

    This report summarizes our recent works of ab initio molecular dynamics inter-atomic potentials development on dilute rare earth element yttrium (Y) etc. doped chromium (Cr) alloy systems, its applications in oxidation and corrosion resistance simulation, and experiment validation on the candidate systems. The simulation methods, experimental validation techniques, achievements already reached, students training, and future improvement are briefly introduced.

  14. Biocompatibility and mechanical properties of diamond-like coatings on cobalt-chromium-molybdenum steel and titanium-aluminum-vanadium biomedical alloys.

    Science.gov (United States)

    Hinüber, C; Kleemann, C; Friederichs, R J; Haubold, L; Scheibe, H J; Schuelke, T; Boehlert, C; Baumann, M J

    2010-11-01

    Diamond-like carbon (DLC) films are favored for wear components because of diamond-like hardness, low friction, low wear, and high corrosion resistance (Schultz et al., Mat-wiss u Werkstofftech 2004;35:924-928; Lappalainen et al., J Biomed Mater Res B Appl Biomater 2003;66B:410-413; Tiainen, Diam Relat Mater 2001;10:153-160). Several studies have demonstrated their inertness, nontoxicity, and the biocompatibility, which has led to interest among manufacturers of surgical implants (Allen et al., J Biomed Mater Res B Appl Biomater 2001;58:319-328; Uzumaki et al., Diam Relat Mater 2006;15:982-988; Hauert, Diam Relat Mater 2003;12:583-589; Grill, Diam Relat Mater 2003;12:166-170). In this study, hydrogen-free amorphous, tetrahedrally bonded DLC films (ta-C) were deposited at low temperatures by physical vapor deposition on medical grade Co28Cr6Mo steel and the titanium alloy Ti6Al4V (Scheibe et al., Surf Coat Tech 1996;85:209-214). The mechanical performance of the ta-C was characterized by measuring its surface roughness, contact angle, adhesion, and wear behavior, whereas the biocompatibility was assessed by osteoblast (OB) attachment and cell viability via Live/Dead assay. There was no statistical difference found in the wettability as measured by contact angle measurements for the ta-C coated and the uncoated samples of either Co28Cr6Mo or Ti6Al4V. Rockwell C indentation and dynamic scratch testing on 2-10 μm thick ta-C films on Co28Cr6Mo substrates showed excellent adhesion with HF1 grade and up to 48 N for the critical load L(C2) during scratch testing. The ta-C coating reduced the wear from 3.5 × 10(-5) mm(3)/Nm for an uncoated control sample (uncoated Co28Cr6Mo against uncoated stainless steel) to 1.1 × 10(-7) mm(3)/Nm (coated Co28Cr6Mo against uncoated stainless steel) in reciprocating pin-on-disk testing. The lowest wear factor of 3.9 × 10(-10) mm(3)/Nm was measured using a ta-C coated steel ball running against a ta-C coated and polished Co28Cr6Mo disk

  15. Transport properties of cobalt at low temperatures

    DEFF Research Database (Denmark)

    Radharkishna, P.; Nielsen, Mourits

    1965-01-01

    Measurements are made of electrical resistivity, absolute thermoelectric power, and thermal conductivity of polycrystalline cobalt between 1.2 and 6 K; results are discussed on basis of inter-electronic scattering.......Measurements are made of electrical resistivity, absolute thermoelectric power, and thermal conductivity of polycrystalline cobalt between 1.2 and 6 K; results are discussed on basis of inter-electronic scattering....

  16. Corrosion resistance and in vitro response of a novel Ti35Nb2Ta3Zr alloy with a low Young's modulus.

    Science.gov (United States)

    Guo, Yongyuan; Chen, Desheng; Lu, Weijie; Jia, Yuhua; Wang, Liqiang; Zhang, Xianlong

    2013-10-01

    β type titanium alloys have attracted much attention in the biomedical field because they consist of non-cytotoxic elements, show high corrosion resistance, and are biologically compatible. In this study, a novel β type titanium alloy (Ti35Nb3Zr2Ta) with a Young's modulus of 48 GPa was fabricated and the alloy's corrosion resistance and in vitro response were determined. The results indicate that the novel alloy exhibits comparable corrosion resistance when compared with Ti6Al4V, but in vitro experiments show that osteoblasts attach, spread, proliferate, and differentiate better on Ti35Nb2Ta3Zr than on Ti6Al4V. The high corrosion resistance and satisfactory biocompatibility make the novel Ti35Nb3Zr2Ta alloy a promising biomaterial for surgical implants.

  17. Abrasive wear resistance and microstructure of Ni-Cr-B-Si hardfacing alloys with additions of Al, Nb, Mo, Fe, Mn and C

    International Nuclear Information System (INIS)

    Berns, H.; Fischer, A.; Theisen, W.

    1987-01-01

    The development of new Ni-base hardfacing alloys for filler wire welding or metal spraying should result in materials with a good resistance against high temperature corrosion and abrasive wear. The first step is to design microstructures, which obtain a satisfactory abrasive wear behaviour at room temperature. Thus, different alloys are melted and scrutinized as to their microstructure and their abrasive wear resistance in laboratory. Compared to commercial Ni-base hardfacing alloys they show a higher volume fraction of coarse hard phases due to the additional, initial solidification of Nb-carbides and Cr-, and Mo-borides. Thus, the abrasive wear resistance is improved. For hard abrasive particles, such as corundum, the Ni-base alloys are more wear resistant than harder Fe-base alloys investigate earlier. This is due to the tougher Ni metal matrix that results in microcracking not to be the most significantly acting wear mechanism

  18. Understanding the resistivity and absolute thermoelectric power of disordered metals and alloys.

    Science.gov (United States)

    Gasser, Jean-Georges

    2008-03-19

    We recall definitions of the electronic transport properties, direct coefficients like electrical and thermal transport conductivities and crossed thermoelectric coefficients like the Seebeck, Peltier and Thomson coefficients. We discuss the links between the different electronic transport coefficients and the experimental problems in measuring these properties in liquid metals. The electronic transport properties are interpreted in terms of the scattering of electrons by 'pseudo-atoms'. The absolute thermoelectric power (ATP), thermopower or Seebeck coefficient is known as the derivative of the electrical resistivity versus energy. The key is to understand the concept of resistivity versus energy. We show that the resistivity follows approximately a 1/E curve. The structure factor modulates this curve and, for a Fermi energy corresponding to noble and divalent metals, induces a positive thermopower when the free electron theory predicts a negative one. A second modulation is introduced by the pseudopotential squared form factor or equivalently by the squared t matrix of the scattering potential. This term sometimes introduces an anti-resonance (divalent metals) which lowers the resistivity, and sometimes a resonance having an important effect on the transition metals. Following the position of the Fermi energy, the thermopower can be positive or negative. For heavy semi-metals, the density of states splits into an s and a p band, themselves different from a free electron E(0.5) curve. The electrons available to be scattered enter the Ziman formula. Thus if the density of states is not a free electron one, a third modulation of the [Formula: see text] curve is needed, which also can change the sign of the thermopower. For alloys, different contributions weighted by the concentrations are needed to explain the concentration dependent resistivity or thermopower. The formalism is the same for amorphous metals. It is possible that this mechanism can be extended to high

  19. Understanding the resistivity and absolute thermoelectric power of disordered metals and alloys

    International Nuclear Information System (INIS)

    Gasser, Jean-Georges

    2008-01-01

    We recall definitions of the electronic transport properties, direct coefficients like electrical and thermal transport conductivities and crossed thermoelectric coefficients like the Seebeck, Peltier and Thomson coefficients. We discuss the links between the different electronic transport coefficients and the experimental problems in measuring these properties in liquid metals. The electronic transport properties are interpreted in terms of the scattering of electrons by 'pseudo-atoms'. The absolute thermoelectric power (ATP), thermopower or Seebeck coefficient is known as the derivative of the electrical resistivity versus energy. The key is to understand the concept of resistivity versus energy. We show that the resistivity follows approximately a 1/E curve. The structure factor modulates this curve and, for a Fermi energy corresponding to noble and divalent metals, induces a positive thermopower when the free electron theory predicts a negative one. A second modulation is introduced by the pseudopotential squared form factor or equivalently by the squared t matrix of the scattering potential. This term sometimes introduces an anti-resonance (divalent metals) which lowers the resistivity, and sometimes a resonance having an important effect on the transition metals. Following the position of the Fermi energy, the thermopower can be positive or negative. For heavy semi-metals, the density of states splits into an s and a p band, themselves different from a free electron E 0.5 curve. The electrons available to be scattered enter the Ziman formula. Thus if the density of states is not a free electron one, a third modulation of the ρ ≅ 1/E curve is needed, which also can change the sign of the thermopower. For alloys, different contributions weighted by the concentrations are needed to explain the concentration dependent resistivity or thermopower. The formalism is the same for amorphous metals. It is possible that this mechanism can be extended to high

  20. The Formation Mechanism and Corrosion Resistance of a Composite Phosphate Conversion Film on AM60 Alloy.

    Science.gov (United States)

    Chen, Jun; Lan, Xiangna; Wang, Chao; Zhang, Qinyong

    2018-03-08

    Magnesium alloy AM60 has high duc and toughness, which is expected to increase in demand for automotive applications. However, it is too active, and coatings have been extensively studied to prevent corrosion. In this work, a Ba-containing composite phosphate film has been prepared on the surface of AM60. The composition and formation mechanism of the film have been investigated using a scanning electronic microscope equipped with energy dispersive X-ray spectroscopy, Fourier transform infrared, X-ray photoelectron spectroscopy, and X-ray diffractometry tests. The corrosion resistance of the film has been measured by electrochemical and immersion tests. The results show that the deposition film has fully covered the substrate but there are some micro-cracks. The structure of the film is complex, and consists of MgHPO₄·3H₂O, MnHPO₄·2.25H₂O, BaHPO₄·3H₂O, BaMg₂(PO₄)₂, Mg₃(PO₄)₂·22H₂O, Ca₃(PO₄)₂·xH₂O, and some amorphous phases. The composite phosphate film has better anticorrosion performance than the AM60 and can protect the bare alloy from corrosion for more than 12 h in 0.6 M NaCl.

  1. Improving of Corrosion Resistance of Aluminum Alloys by Removing Intermetallic Compound

    International Nuclear Information System (INIS)

    Seri, Osami

    2008-01-01

    It is well known that iron is one of the most common impurity elements sound in aluminum and its alloys. Iron in the aluminum forms an intermetallic compounds such as FeAl 3 . The FeAl 3 particles on the aluminum surface are one of the most detrimental phases to the corrosion process and anodizing procedure for aluminum and its alloys. Trial and error surface treatment will be carried out to find the preferential and effective removal of FeAl 3 particles on the surfaces without dissolution of aluminum matrix around the particles. One of the preferable surface treatments for the aim of getting FeAl 3 free surface was an electrochemical treatment such as cathodic current density of -2 kAm -2 in a 20-30 mass% HNO 3 solution for the period of 300s. The corrosion characteristics of aluminum surface with FeAl 3 free particles are examined in a 0.1 kmol/m 3 NaCl solution. It is found that aluminum with free FeAl 3 particles shows higher corrosion resistance than aluminum with FeAl 3 particles

  2. Stainless alloys with shape memory effect: relationship between thermal-mechanical treatment, martensite content {epsilon} and hardness; Ligas inoxidaveis com efeito de memoria de forma: relacao entre tratamento termo-mecanico, teor de martensita {epsilon} e dureza

    Energy Technology Data Exchange (ETDEWEB)

    Otubo, Jorge; Mei, Paulo Roberto [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica; Koshimizu, Sadamu; Martinez, Luis Gallego [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    1996-12-31

    The stainless alloys with shape memory effect (SME) developed in Japan since 1990, and in Brazil by this group since 1994, have presented better recovery than the conventional Fe-Mn-Si alloys. These alloys present outstanding corrosion resistance, which allows a wide range of practical applications. This work analyses the relationship between the thermal-mechanical treatment such as solubilization and thermal cycling for SME enhancing, the martensite content {epsilon} and the hardness, for two stainless alloys, with and without cobalt addition, respectively. The results show that the hardness variations are much more dependents on the austenitic matrix than the martensite content {epsilon} 12 refs., 1 tab.

  3. Cobalt-60 control in Ontario Hydro reactors

    International Nuclear Information System (INIS)

    Lacy, C.S.

    1988-01-01

    This paper discusses the impact of specifying reduced Cobalt-59 in the primary heat transport circuit materials of construction on the radiation fields developed around the primary circuit. An eight-fold reduction in steam generator radiation fields due to Cobalt-60 has been observed for two identical sets of reactors, one with and one without Cobalt-59 control. The comparison is between eight reactors at the Pickering Nuclear Generating Station (PNGS). Units 5 to 8 (PNGS-B) are identical to Units 1 to 4 (PNGS-A) except that PNGS-B has reduced impurity Cobalt-59 in the alloys of construction and a reduced use of stellite. The effects of chemistry control are also discussed

  4. Effect of Annealing on the Pitting Corrosion Resistance of Anodized Aluminum-Magnesium Alloy Processed by Equal Channel Angular Pressing

    Energy Technology Data Exchange (ETDEWEB)

    Son, In Joon; Nakano, Hiroaki; Oue, Satoshi; Fukushima, Hisaaki; Horita, Zenji [Kyushu University, Fukuoka (Japan); Kobayashi, Shigeo [Kyushu Sangyo University, Fukuoka (Japan)

    2007-12-15

    The effect of annealing on the pitting corrosion resistance of anodized Al-Mg alloy (AA5052) processed by equal-channel angular pressing (ECAP) was investigated by electrochemical techniques in a solution containing 0.2 mol/L of AlCl{sub 3} and also by surface analysis. The Al-Mg alloy was annealed at a fixed temperature between 473 and 573 K for 120 min in air after ECAP. Anodizing was conducted for 40 min at 100-400 A/m{sup 2} at 293 K in a solution containing 1.53 mol/L of H{sub 2}SO{sub 4} and 0.0185 mol/L of Al{sub 2}(SO{sub 4}){sub 3}. The internal stress generated in anodic oxide films during anodization was measured with a strain gauge to clarify the effect of ECAP on the pitting corrosion resistance of anodized Al-Mg alloy. The time required to initiate the pitting corrosion of anodized Al-Mg alloy was shorter in samples subjected to ECAP, indicating that ECAP decreased the pitting corrosion resistance. however, the pitting corrosion resistance was greatly improved by annealing after ECAP. The time required to initiate pitting corrosion increased with increasing annealing temperature. The strain gauge attached to Al-Mg alloy revealed that the internal stress present in the anodic oxide films was compressive stress, and that the stress was larger with ECAP than without. The compressive internal stress gradually decreased with increasing annealing temperature. Scanning electron microscopy showed that cracks occurred in the anodic oxide film on Al-Mg alloy during initial corrosion and that the cracks were larger with ECAP than without. The ECAP process of severe plastic deformation produces large internal stresses in the Al-Mg alloy: the stresses remain in the anodic oxide films, increasing the likelihood of cracks. it is assumed that the pitting corrosion is promoted by these cracks as a result of the higher internal stress resulting from ECAP. The improvement in the pitting corrosion resistance of anodized AlMg alloy as a result of annealing appears to be

  5. Effect of Annealing on the Pitting Corrosion Resistance of Anodized Aluminum-Magnesium Alloy Processed by Equal Channel Angular Pressing

    International Nuclear Information System (INIS)

    Son, In Joon; Nakano, Hiroaki; Oue, Satoshi; Fukushima, Hisaaki; Horita, Zenji; Kobayashi, Shigeo

    2007-01-01

    The effect of annealing on the pitting corrosion resistance of anodized Al-Mg alloy (AA5052) processed by equal-channel angular pressing (ECAP) was investigated by electrochemical techniques in a solution containing 0.2 mol/L of AlCl 3 and also by surface analysis. The Al-Mg alloy was annealed at a fixed temperature between 473 and 573 K for 120 min in air after ECAP. Anodizing was conducted for 40 min at 100-400 A/m 2 at 293 K in a solution containing 1.53 mol/L of H 2 SO 4 and 0.0185 mol/L of Al 2 (SO 4 ) 3 . The internal stress generated in anodic oxide films during anodization was measured with a strain gauge to clarify the effect of ECAP on the pitting corrosion resistance of anodized Al-Mg alloy. The time required to initiate the pitting corrosion of anodized Al-Mg alloy was shorter in samples subjected to ECAP, indicating that ECAP decreased the pitting corrosion resistance. however, the pitting corrosion resistance was greatly improved by annealing after ECAP. The time required to initiate pitting corrosion increased with increasing annealing temperature. The strain gauge attached to Al-Mg alloy revealed that the internal stress present in the anodic oxide films was compressive stress, and that the stress was larger with ECAP than without. The compressive internal stress gradually decreased with increasing annealing temperature. Scanning electron microscopy showed that cracks occurred in the anodic oxide film on Al-Mg alloy during initial corrosion and that the cracks were larger with ECAP than without. The ECAP process of severe plastic deformation produces large internal stresses in the Al-Mg alloy: the stresses remain in the anodic oxide films, increasing the likelihood of cracks. it is assumed that the pitting corrosion is promoted by these cracks as a result of the higher internal stress resulting from ECAP. The improvement in the pitting corrosion resistance of anodized AlMg alloy as a result of annealing appears to be attributable to a decrease in

  6. Fatigue resistance of rotary instruments manufactured using different nickel-titanium alloys: a comparative study.

    Science.gov (United States)

    Plotino, Gianluca; Testarelli, Luca; Al-Sudani, Dina; Pongione, Gianlcarlo; Grande, Nicola M; Gambarini, Gianluca

    2014-01-01

    The aim of this study was to investigate whether cyclic fatigue resistance is increased for Controlled Memory (CM) Nickel-Titanium (NiTi) instruments, compared to instruments produced using traditional NiTi and instruments produced using M-Wire alloy. Two groups of NiTi endodontic instruments consisting of identical instrument sizes (constant 0.06 taper and 0.25 tip diameter and constant 0.04 taper and 0.40 tip diameter) were tested: group A compared Hyflex™ CM, Vortex ™ and ProFile ™ size 25 and 0.06 taper and group B compared Hyflex™ CM, Vortex™ and ProFile™ size 40 and 0.04 taper. 10 files from each different subgroup were tested for cyclic fatigue resistance. Mean and standard deviations of the Number of Cycles to Failure (NCF) were calculated for each group and data were statistically analysed (p 0.05) was noted between Vortex™ and ProFile™ in the tested sizes. The new manufacturing process involving memory shape heat treatment produced new NiTi rotary files (Hyflex™ CM) significantly more resistant to fatigue than instruments produced with other proprietary methods of treatment (Vortex™) and with the traditional NiTi grinding process (ProFile™).

  7. Enhanced corrosion resistance of magnesium alloy AM60 by cerium(III) in chloride solution

    Energy Technology Data Exchange (ETDEWEB)

    Heakal, F. El-Taib, E-mail: fakihaheakal@yahoo.com [Chemistry Department, Faculty of Science, Cairo University, Giza 12613 (Egypt); Shehata, O.S. [Physical Chemistry Department, National Research Centre, Dokki, Giza (Egypt); Tantawy, N.S. [Girl' s College of Arts, Science and Education, Ain Shams University, Asma Fahmi Street, Cairo (Egypt)

    2012-03-15

    Highlights: Black-Right-Pointing-Pointer Corrosion rate of AM60 in Cl{sup -} solution decreases with increasing [Ce{sup 3+}] up to 1 mM. Black-Right-Pointing-Pointer Beyond that level the corrosion rate increases and then stabilizes. Black-Right-Pointing-Pointer The spontaneously formed film characterises by increasing resistance with time. Black-Right-Pointing-Pointer The converted film after 10 d immersion exhibits self-healing in plain Cl{sup -} solution. Black-Right-Pointing-Pointer Ce(III) should be present in the corrodent to form a more compact surface coating. - Abstract: Cerium(III) was utilised to enhance the corrosion resistance of AM60 in NaCl solution. Ce{sup 3+} can suppress corrosion deterioration up to 1.0 mM. Beyond that level corrosion rate increases till a steady value. Surface film resistance increases with time evolution until 24 h, then decreases and stabilizes. The converted film after 240 h immersion exhibits self-healing and thickening when re-exposed to plain chloride solution. SEM and EDX confirmed that when Ce is present as additive in solution, more compact coating is formed better than its presence as a post coating on the alloy surface before being immersed in the corrosive environment.

  8. Enhanced corrosion resistance of magnesium alloy AM60 by cerium(III) in chloride solution

    International Nuclear Information System (INIS)

    Heakal, F. El-Taib; Shehata, O.S.; Tantawy, N.S.

    2012-01-01

    Highlights: ► Corrosion rate of AM60 in Cl − solution decreases with increasing [Ce 3+ ] up to 1 mM. ► Beyond that level the corrosion rate increases and then stabilizes. ► The spontaneously formed film characterises by increasing resistance with time. ► The converted film after 10 d immersion exhibits self-healing in plain Cl − solution. ► Ce(III) should be present in the corrodent to form a more compact surface coating. - Abstract: Cerium(III) was utilised to enhance the corrosion resistance of AM60 in NaCl solution. Ce 3+ can suppress corrosion deterioration up to 1.0 mM. Beyond that level corrosion rate increases till a steady value. Surface film resistance increases with time evolution until 24 h, then decreases and stabilizes. The converted film after 240 h immersion exhibits self-healing and thickening when re-exposed to plain chloride solution. SEM and EDX confirmed that when Ce is present as additive in solution, more compact coating is formed better than its presence as a post coating on the alloy surface before being immersed in the corrosive environment.

  9. Wear resistance analysis of the aluminum 7075 alloy and the nanostructured aluminum 7075 - silver nanoparticles composites

    Directory of Open Access Journals (Sweden)

    Estrada-Ruiz R.H.

    2016-01-01

    Full Text Available Nanostructured composites of the aluminum 7075 alloy and carbon-coated silver nanoparticles were synthetized by the mechanical milling technique using a high-energy mill SPEX 8000M; the powders generated were compacted, sintered and hot-extruded to produce 1 cm-diameter bars. The composites were then subjected to a wear test using a pin-on-disc device to validate the hypothesis that second phase-ductile nanometric particles homogenously distributed throughout the metalmatrix improve the wear resistance of the material. It was found that silver nanoparticles prevent the wear of the material by acting as an obstacle to dislocations movement during the plastic deformation of the contact surface, as well as a solid lubricant when these are separated from the metal-matrix.

  10. Standard classification of resistance to stress-corrosion cracking of heat-treatable Aluminum alloys

    CERN Document Server

    American Society for Testing and Materials. Philadelphia

    1999-01-01

    1.1 This classification covers alphabetical ratings of the relative resistance to SCC of various mill product forms of the wrought 2XXX, 6XXX, and 7XXX series heat-treated aluminum alloys and the procedure for determining the ratings. 1.2 The ratings do not apply to metal in which the metallurgical structure has been altered by welding, forming, or other fabrication processes. 1.3 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only. 1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

  11. The effect of 3 wt.% Cu addition on the microstructure, tribological property and corrosion resistance of CoCrW alloys fabricated by selective laser melting.

    Science.gov (United States)

    Luo, Jiasi; Wu, Songquan; Lu, Yanjin; Guo, Sai; Yang, Yang; Zhao, Chaoqian; Lin, Junjie; Huang, Tingting; Lin, Jinxin

    2018-03-19

    Microstructure, tribological property and corrosion resistance of orthopedic implant materials CoCrW-3 wt.% Cu fabricated by selective laser melting (SLM) process were systematically investigated with CoCrW as control. Equaxied γ-phase together with the inside {111}  type twin and platelet ε-phase was found in both the Cu-bearing and Cu-free alloys. Compared to the Cu-free alloy, the introduction of 3 wt.% Cu significantly increased the volume fraction of the ε-phase. In both alloys, the hardness of ε-phase zone was rather higher (~4 times) than that of γ-phase zone. The wear factor of 3 wt.% Cu-bearing alloy possessed smaller wear factor, although it had higher friction coefficient compared with Cu-free alloys. The ε-phase in the CoCr alloy would account for reducing both abrasive and fatigue wear. Moreover, the Cu-bearing alloy presented relatively higher corrosion potential E corr and lower corrosion current density I corr compared to the Cu-free alloy. Accordingly, 3 wt.% Cu addition plays a key role in enhancing the wear resistance and corrosion resistance of CoCrW alloys, which indicates that the SLM CoCrW-3Cu alloy is a promising personalized alternative for traditional biomedical implant materials.

  12. Investigation of the corrosion resistance of Ti-13Nb-13Zr alloy by electrochemical techniques and surface analysis

    International Nuclear Information System (INIS)

    Assis, Sergio Luiz de

    2006-01-01

    In this work, the in vitro corrosion resistance of the Ti-13Nb-13Zr alloy, manufactured at a national laboratory, and used for orthopedic applications, has been investigated in solutions that simulate the body fluids. The electrolytes used were 0.9 % (mass) NaCl, Hanks' solution, a culture medium (MEM), and the two last electrolytes, without and with addition of hydrogen peroxide. The aim of peroxide addition was to simulate the conditions found when inflammatory reactions occur due to surgical procedures. The corrosion resistance of alloys commercially in use as biomaterials, Ti-6Al-7Nb and Ti-6Al-4V, as well as of the pure titanium (Ti-cp), was also studied for comparison with the Ti-13Nb-13Zr alloy. The corrosion resistance characterization was carried out by electrochemical and surface analysis techniques. The electrochemical tests used were: open circuit potential measurements as a function of tim; potentiodynamic polarization; and electrochemical impedance spectroscopy (EIE). The impedance experimental diagrams were interpreted using equivalent electric circuits that simulate an oxide film with a duplex structure composed of an internal and compact, barrier type layer, and an external porous layer. The results showed that the corrosion resistance is due mainly to the barrier type layer. The titanium alloys and the Ti-cp showed high corrosion resistance in all electrolytes used. The oxides formed on the Ti-13Nb-13Zr, either naturally or during immersion in MEM ar Hank's solution was characterized by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (MEV). The results showed that the presence of hydrogen peroxide in MEM promotes the growth of the porous layer and incorporation of mineral ions, besides favouring hydroxyapatite formation. The cytotoxicity of the Ti-13Nb-13Zr alloy was also evaluated and it was shown to be non-toxic. (author)

  13. Antibacterial activity, corrosion resistance and wear behavior of spark plasma sintered Ta-5Cu alloy for biomedical applications.

    Science.gov (United States)

    Cui, Jing; Zhao, Liang; Zhu, Weiwei; Wang, Bi; Zhao, Cancan; Fang, Liming; Ren, Fuzeng

    2017-10-01

    Tantalum has been widely used in orthopedic and dental implants. However, the major barrier to the extended use of such medical devices is the possibility of bacterial adhesion to the implant surface which will cause implant-associated infections. To solve this problem, bulk Ta-5Cu alloy has been fabricated by a combination of mechanical alloying and spark plasma sintering. The effect of the addition of Cu on the hardness, antibacterial activity, cytocompatibility, corrosion resistance and wear performance was systematically investigated. The sintered Ta-5Cu alloy shows enhanced antibacterial activity against E. Coli due to the sustained release of Cu ions. However, the addition of Cu would produce slight cytotoxicity and decrease corrosion resistance of Ta. Furthermore, pin-on-disk wear tests show that Ta-5Cu alloy has a much lower coefficient of friction but a higher wear rate and shows a distinct wear mode from that of Ta upon sliding against stainless steel 440C. Wear-induced plastic deformation leads to elongation of Ta and Cu grains along the sliding direction and nanolayered structures were observed upon approaching the sliding surface. The presence of hard oxides also shows a profound effect on the plastic flow of the base material and results in localized vortex patterns. The obtained results are expected to provide deep insights into the development of novel Ta-Cu alloy for biomedical applications. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. The fluoride coated AZ31B magnesium alloy improves corrosion resistance and stimulates bone formation in rabbit model.

    Science.gov (United States)

    Sun, Wei; Zhang, Guangdao; Tan, Lili; Yang, Ke; Ai, Hongjun

    2016-06-01

    This study aimed to evaluate the effect of fluorine coated Mg alloy and clarify its mechanism in bone formation. We implanted the fluorine coated AZ31B Mg alloy screw (group F) in rabbit mandibular and femur in vivo. Untreated AZ31B Mg alloy screw (group A) and titanium screw (group T) were used as control. Then, scanning electron microscopy, the spectral energy distribution analysis, hard and decalcified bone tissues staining were performed. Immunohistochemistry was employed to examine the protein expressions of bone morphogenetic protein 2 (BMP-2) and collagen type I in the vicinity of the implant. Compared with the group A, the degradation of the alloy was reduced, the rates of Mg corrosion and Mg ion release were slowed down, and the depositions of calcium and phosphate increased in the group F in the early stage of implantation. Histological results showed that fluorine coated Mg alloy had well osteogenic activity and biocompatibility. Moreover, fluoride coating obviously up-regulated the expressions of collagen type I and BMP-2. This study confirmed that the fluorine coating might improve the corrosion resistance of AZ31B Mg alloy and promote bone formation by up-regulated the expressions of collagen type I and BMP-2. Copyright © 2016. Published by Elsevier B.V.

  15. The effect lead impurities on the corrosion resistance of alloy 600 and alloy 690 in high temperature water

    International Nuclear Information System (INIS)

    Sakai, T.; Nakagomi, N.; Kikuchi, T.; Aoki, K.; Nakayasu, F.; Yamakawa, K.

    1998-01-01

    Degradation of nickel-based alloy steam generator (SG) tubing caused by lead-induced corrosion has been reported recently in some PWR plants. Several laboratory studies also have shown that lead causes intergranular or transgranular stress corrosion cracking (IGSCC or TGSCC) of the tubing materials. Information from previous studies suggests two possible explanations for the mechanism of lead-induced corrosion. One is selective dissolution of tube metal elements, resulting in formation of a lead-containing nickel-depleted oxide film as observed in mildly acidic environments. The other explanation is an increase in potential, as has been observed in lead-contaminated caustic environments, although not in all volatile treatment (AVT) water such as the ammonium-hydrazine water chemistry. These observation suggest that an electrochemical reaction between metal elements and dissolved lead might be the cause of lead-induced corrosion. The present work was undertaken to clarify the lead-induced corrosion mechanism of nickel-based alloys from an electrochemical viewpoint, focusing on mildly acidic and basic environments. These are the probable pH conditions in the crevice region between the tube and tube support plate of the SG where corrosion damage could occur. Measurements of corrosion potential and electrochemical polarization of nickel-based alloys were performed to investigate the effect of lead on electrochemical behavior of the alloys. Then, constant extension rate tests (CERT) were carried out to determine the corrosion susceptibility of the alloys in a lead-contaminated environment. (J.P.N.)

  16. Development of Advanced Wear and Corrosion Resistant Systems Through Laser Surface Alloying and Materials Simulations

    Energy Technology Data Exchange (ETDEWEB)

    R. P. Martukanitz and S. Babu

    2007-05-03

    Laser surfacing in the form of cladding, alloying, and modifications are gaining widespread use because of its ability to provide high deposition rates, low thermal distortion, and refined microstructure due to high solidification rates. Because of these advantages, laser surface alloying is considered a prime candidate for producing ultra-hard coatings through the establishment or in situ formation of composite structures. Therefore, a program was conducted by the Applied Research Laboratory, Pennsylvania State University and Oak Ridge National Laboratory to develop the scientific and engineering basis for performing laser-based surface modifications involving the addition of hard particles, such as carbides, borides, and nitrides, within a metallic matrix for improved wear, fatigue, creep, and corrosion resistance. This has involved the development of advanced laser processing and simulation techniques, along with the refinement and application of these techniques for predicting and selecting materials and processing parameters for the creation of new surfaces having improved properties over current coating technologies. This program has also resulted in the formulation of process and material simulation tools capable of examining the potential for the formation and retention of composite coatings and deposits produced using laser processing techniques, as well as positive laboratory demonstrations in producing these coatings. In conjunction with the process simulation techniques, the application of computational thermodynamic and kinetic models to design laser surface alloying materials was demonstrated and resulted in a vast improvement in the formulation of materials used for producing composite coatings. The methodology was used to identify materials and to selectively modify microstructures for increasing hardness of deposits produced by the laser surface alloying process. Computational thermodynamic calculations indicated that it was possible to induce the

  17. Cobalt-boron amorphous alloy prepared in water/cetyl-trimethyl-ammonium bromide/n-hexanol microemulsion as anode for alkaline secondary batteries

    International Nuclear Information System (INIS)

    Tong, D.G.; Wang, D.; Chu, W.; Sun, J.H.; Wu, P.

    2010-01-01

    Amorphous cobalt-boron (Co-B) with uniform nanoparticles was prepared for the first time via reduction of cobalt acetate by potassium borohydride in the water/cetyl-trimethyl-ammonium bromide/n-hexanol microemulsion system. The sample was characterized by X-ray diffraction, transmission electron microscopy, nitrogen adsorption-desorption, X-ray photoelectron spectroscopy, inductively coupled plasma, cyclic voltammetry, differential scanning calorimetry, temperature-programmed desorption, scanning electron microscopy, charge-discharge test and electrochemical impedance spectra. The results demonstrate that electrochemical activity of the as-synthesized Co-B was higher than that of the regular Co-B prepared in aqueous solution. It indicates that the homogeneous distribution and large specific surface area helped the electrochemical hydrogen storage of the as-synthesized Co-B. Furthermore, the as-synthesized Co-B even had 347 mAh g -1 after 50 cycles, while the regular Co-B prepared in aqueous solution only had 254 mAh g -1 after 30 cycles at a current of 100 mA g -1 . The better cycling performance can be ascribed to its smaller interfacial impedance between electrode and electrolyte.

  18. Preliminary evaluation of cavitation-erosion resistance of Ti-alloys in mercury for the Spallation Neutron Source

    International Nuclear Information System (INIS)

    Pawel, S.J.; Mansur, L.K.

    2010-01-01

    A number of Ti-based alloys in both the mill-annealed and 20% cold-worked conditions were subjected to sonication conditions in Hg using a vibratory horn to assess relative cavitation-erosion resistance. Weight loss as a function of exposure time decreased monotonically with increasing hardness for all alloys/conditions examined, with Ti-6Al-4V (Grade 5) and Ti-6Al-2Sn-4Zr-2Mo yielding the best resistance to cavitation-erosion as evidenced by low weight losses and little or no tendency to form pits on the exposed surface. Unalloyed Ti (Grade 4) and Ti-0.12Pd (Grade 7) exhibited greater weight losses by a factor of about two and about five, respectively, with Ti-0.12Pd particularly prone to pitting development. The mean erosion rates of the best two Ti-alloys examined were about a factor of three higher than identically tested 316LN stainless steel following a low temperature carburizing treatment, but this difference is considered minor given that the rate for both materials is very low/manageable and represents a through-thickness property for the Ti-alloys. A nitriding surface treatment was also evaluated as a potential method to further increase the cavitation-erosion resistance of these alloys in Hg, but the selected treatment proved largely ineffective as measured by rapid weight loss. Recommendations for further work to evaluate the efficacy of Ti-based alloys for use in high-powered targets for the Spallation Neutron Source are given.

  19. Influence of rare earth additions on the oxidation resistance of chromia forming alloys

    International Nuclear Information System (INIS)

    Pillis, Marina Fuser

    1995-01-01

    The addition of rare earths to alloys, either in elemental form or as surface coatings reduces the oxidation rate of chromia forming alloys. The rare earths either act as nucleation sites for surface oxides or get incorporates into the surface oxide and diffuse to oxide grain boundaries. If the latter occurs, a change in the defect structure close to the grain boundaries, probably takes place. In this manner, the rare earths inhibits the movement of chromium ions to the oxide/gas interface. The influence of rare earth additions to AISI 316, AISI 316L and Ni-20 Cr on their oxidation behavior has been studied., AISI 316+Ce, AISI 316+Y, Ni-20 Cr and Ni-20 Cr-2 Al-1 Ce were prepared by melting and AISI 316L, AISI 316L+Ce O 2 and AISI 316L+Y 2 O 3 by powder compaction. The effect of superficial deposits of rare earth oxides was also studied. The alloys were coated with rare earth oxides by high temperature conversion of the respective rare earth nitrates. Isothermal oxidation tests were carried out at 900-1100 deg C and the cyclic oxidation tests consisted of 6 cycles of 2 hours each at 900 deg C, followed by cooling to room temperature. All the tests were carried out in air. Oxidation behavior was evaluated gravimetrically. Scanning electron microscopy was used to study surface morphology. Energy dispersive analysis and X-ray diffraction techniques were used to identify oxide constituents. Overall, it has been observed that with the addition of rare earths, oxidation resistance increases by decreasing oxidation rates and increasing oxide adhesion. Addition of rare earths to AISI 316 prepared by melting resulted in rapid formation of a chromium rich oxide layered near the metal/oxide interface which reduced overall oxidation rate. The addition of Ce O 2 to AISI 316L was found to improve oxidation behavior after 10 hours at 1100 deg C and also inhibit the formation of volatile Cr O 3 . The isothermal oxidation behavior of rare earth oxide covered Ni-20 Cr at 900 deg C

  20. The fluoride coated AZ31B magnesium alloy improves corrosion resistance and stimulates bone formation in rabbit model

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Wei; Zhang, Guangdao [Department of Prosthodontics, School of Stomatology, China Medical University, Shenyang 110001 (China); Tan, Lili; Yang, Ke [Institute of Metal Research, Chinese Academy of Sciences, Shenyang 110016 (China); Ai, Hongjun, E-mail: aihongjuna@sina.com [Department of Prosthodontics, School of Stomatology, China Medical University, Shenyang 110001 (China)

    2016-06-01

    This study aimed to evaluate the effect of fluorine coated Mg alloy and clarify its mechanism in bone formation. We implanted the fluorine coated AZ31B Mg alloy screw (group F) in rabbit mandibular and femur in vivo. Untreated AZ31B Mg alloy screw (group A) and titanium screw (group T) were used as control. Then, scanning electron microscopy, the spectral energy distribution analysis, hard and decalcified bone tissues staining were performed. Immunohistochemistry was employed to examine the protein expressions of bone morphogenetic protein 2 (BMP-2) and collagen type I in the vicinity of the implant. Compared with the group A, the degradation of the alloy was reduced, the rates of Mg corrosion and Mg ion release were slowed down, and the depositions of calcium and phosphate increased in the group F in the early stage of implantation. Histological results showed that fluorine coated Mg alloy had well osteogenic activity and biocompatibility. Moreover, fluoride coating obviously up-regulated the expressions of collagen type I and BMP-2. This study confirmed that the fluorine coating might improve the corrosion resistance of AZ31B Mg alloy and promote bone formation by up-regulated the expressions of collagen type I and BMP-2. - Highlights: • Fluoride coating inhibited the degradation of the alloy in the early implantation. • Fluorine coating could slow down the rate of Mg corrosion and Mg ion release. • Fluorine coating could promote the deposition of Ca and P in vivo. • Fluorine coated Mg alloy had well osteogenic activity and biocompatibility. • Fluorine coating up-regulated the expression of BMP-2 and collagen type I protein.

  1. Biocompatibility of dental alloys

    Energy Technology Data Exchange (ETDEWEB)

    Braemer, W. [Heraeus Kulzer GmbH and Co. KG, Hanau (Germany)

    2001-10-01

    Modern dental alloys have been used for 50 years to produce prosthetic dental restorations. Generally, the crowns and frames of a prosthesis are prepared in dental alloys, and then veneered by feldspar ceramics or composites. In use, the alloys are exposed to the corrosive influence of saliva and bacteria. Metallic dental materials can be classified as precious and non-precious alloys. Precious alloys consist of gold, platinum, and small amounts of non-precious components such as copper, tin, or zinc. The non-precious alloys are based on either nickel or cobalt, alloyed with chrome, molybdenum, manganese, etc. Titanium is used as Grade 2 quality for dental purposes. As well as the dental casting alloys, high purity electroplated gold (99.8 wt.-%) is used in dental technology. This review discusses the corrosion behavior of metallic dental materials with saliva in ''in vitro'' tests and the influence of alloy components on bacteria (Lactobacillus casei and Streptococcus mutans). The test results show that alloys with high gold content, cobalt-based alloys, titanium, and electroplated gold are suitable for use as dental materials. (orig.)

  2. [The effect of C-SiO2composite films on corrosion resistance of dental Co-Cr alloy].

    Science.gov (United States)

    Huang, Yi; Hu, Jing-Yu; Liu, Yu-Pu; Zhao, Dong-Yuan; Yu, You-Cheng; Bi, Wei

    2016-10-01

    To study the effect of carbon-silica composite films on corrosion resistance of Co-Cr alloy in simulated oral environment and provide evidences for clinical application of this new material. Co-Cr alloy specimens were cut into appropriate size of 20 mm × 20 mm × 0.5 mm. Then, the carbon-silica composite films were spin-coated onto the specimens. Subsequently, ICP-AES was used to observe the Co, Cr, Mo ion concentrations. Finally, Tafel polarization curves of the specimens were used to measure the electrochemical corrosion resistance by electrochemical workstation. SAS8.0 software package was used for statistical analysis. The results of ICP-AES showed that the ion concentrations of Co, Cr, Mo of specimens coated with composite films in the testing liquid were significantly smaller than that of Co-Cr alloy specimens. Tafel polarization curves showed that in the specimens coated with composite films, the corrosion potential moved in the positive direction and increased from -0.261 V to -0.13 V. At the same time, the corrosion current density decreased from -5.0017μA/cm 2 to -5.3006 μA/cm 2 . Carbon-silica composite films (silica=61.71wt %) can reduce the release of metal ions significantly and improve the corrosion resistance of Co-Cr alloys effectively. Carbon-silica composite films may be a promising dental material.

  3. Enhanced mechanical properties and increased corrosion resistance of a biodegradable magnesium alloy by plasma electrolytic oxidation (PEO)

    International Nuclear Information System (INIS)

    White, Leon; Koo, Youngmi; Neralla, Sudheer; Sankar, Jagannathan; Yun, Yeoheung

    2016-01-01

    Highlights: • Plasma electrolytic oxidation (PEO) method was developed to control corrosion, porosity, and mechanical property. • Mechanical properties of PEO-coated AZ31 alloys were affected by the different electrolyte. • Mechanical properties and corrosion resistance of PEO-coated AZ31 alloys were compared with uncoated one. - Abstract: We report the enhanced mechanical properties of AZ31 magnesium alloys by plasma electrolytic oxidation (PEO) coating in NaOH, Na 2 SiO 3 , KF and NaH 2 PO 4 ·2H 2 O containing electrolytes. Mechanical properties including wear resistance, surface hardness and elastic modulus were increased for PEO-coated AZ31 Mg alloys (PEO-AZ31). DC polarization in Hank's solution indicating that the corrosion resistance significantly increased for PEO-coating in KF-contained electrolyte. Based on these results, the PEO coating method shows promising potential for use in biodegradable implant applications where tunable corrosion and mechanical properties are needed.

  4. Evaluation of corrosion resistance of implant-use Ti-Zr binary alloys with a range of compositions.

    Science.gov (United States)

    Akimoto, Teisuke; Ueno, Takeshi; Tsutsumi, Yusuke; Doi, Hisashi; Hanawa, Takao; Wakabayashi, Noriyuki

    2018-01-01

    Although titanium-zirconium (Ti-Zr) alloy has been adopted for clinical applications, the ideal proportion of Zr in the alloy has not been identified. In this study, we investigated the biocompatibility of Ti-Zr alloy by evaluating its corrosion resistance to better understand whether there is an optimal range or value of Zr proportion in the alloy. We prepared pure Ti, Ti-30Zr, Ti-50Zr, Ti-70Zr, and pure Zr (mol% of Zr) samples and subjected them to anodic polarization and immersion tests in a lactic acid + sodium chloride (NaCl) solution and artificial saliva. We observed pitting corrosion in the Ti-70Zr and Zr after exposure to both solutions. After the immersion test, we found that pure Ti exhibited the greatest degree of dissolution in the lactic acid + NaCl solution, with the addition of Zr dramatically reducing Ti ion dissolution, with the reduction ultimately exceeding 90% in the case of the Ti-30Zr. Hence, although the localized corrosion resistance under severe conditions was compromised when the Zr content was more than 70%, metal ion release reduced owing to Zr addition and the corresponding formation of a stable passive layer. The results suggest that Ti-30Zr or a Zr proportion of less than 50% would offer an ideal level of corrosion resistance for clinical applications. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 73-79, 2018. © 2016 Wiley Periodicals, Inc.

  5. Wear Resistant Thermal Sprayed Composite Coatings Based on Iron Self-Fluxing Alloy and Recycled Cermet Powders

    Directory of Open Access Journals (Sweden)

    Heikki SARJAS

    2012-03-01

    Full Text Available Thermal spray and WC-Co based coatings are widely used in areas subjected to abrasive wear. Commercial  cermet thermal spray powders for HVOF are relatively expensive. Therefore applying these powders in cost-sensitive areas like mining and agriculture are hindered. Nowadays, the use of cheap iron based self-fluxing alloy powders for thermal spray is limited. The aim of this research was to study properties of composite powders based on self-fluxing alloys and recycled cermets and to examine the properties of thermally sprayed (HVOF coatings from composite powders based on iron self-fluxing alloy and recycled cermet powders (Cr3C2-Ni and WC-Co. To estimate the properties of  recycled cermet powders, the sieving analysis, laser granulometry and morphology were conducted. For deposition of coatings High Velocity Oxy-Fuel spray was used. The structure and composition of powders and coatings were estimated by SEM and XRD methods. Abrasive wear performance of coatings was determined and compared with wear resistance of coatings from commercial powders. The wear resistance of thermal sprayed coatings from self-fluxing alloy and recycled cermet powders at abrasion is comparable with wear resistance of coatings from commercial expensive spray powders and may be an alternative in tribological applications in cost-sensitive areas.DOI: http://dx.doi.org/10.5755/j01.ms.18.1.1338

  6. Effect of inoculation on microstructure, mechanical and corrosion properties of high manganese ductile Ni-resist alloy

    International Nuclear Information System (INIS)

    Mohd Rashidi, M.; Idris, Mohd Hasbullah

    2013-01-01

    Highlights: • Experimental purpose of mechanical properties of modified ductile Ni-resist. • Evaluation of the influence of high manganese content on mechanical properties and corrosion behaviour. • Metallurgical, phases analysis and microstructural parameters determination. - Abstract: The performance of modified ductile Ni-resist (DNR) adapted with higher manganese content, may be improved by inoculation in order that it may be of use in corrosive and high temperature application. In this study, DNR cast alloy was casting to different manganese content before undergoing inoculation process with various inoculation percentages. Scanning Electron Microscope/Energy Dispersive X-ray Spectroscopy SEM/EDS characterized the corrosion products. The results showed that increasing inoculation did decreased carbide formation led to improved tensile value and decreased hardness value. Moreover, inoculation led to uniform distribution of graphite resulted in lower corrosion rates. It can be concluded that inoculation process improved the mechanical properties of the alloy and satisfy the corrosion resistance criteria required for corrosive environment

  7. Effect of surface treatment on the interfacial contact resistance and corrosion resistance of Fe–Ni–Cr alloy as a bipolar plate for polymer electrolyte membrane fuel cells

    International Nuclear Information System (INIS)

    Yang, Meijun; Zhang, Dongming

    2014-01-01

    The bipolar plate is an important component of the PEMFC (polymer electrolyte membrane fuel cell) because it supplies the pathway of electron flow between each unit cell. Fe–Ni–Cr alloy is considered as a good candidate material for bipolar plate, but it is limited to use as a bipolar plate due to its high ICR (interfacial contact resistance) and corrosion problem. In order to explore a cost-effective method on surface modification, various chemical and electrochemical treatments are performed on Fe–Ni–Cr alloy to acquire the effect of the surface modification on the ICR and corrosion behavior. The ICR and corrosion resistance of Fe–Ni–Cr alloy can be effectively controlled by the chemical treatment of immersion in the mixed acid solution with 10 vol% HNO 3 , 2 vol% HCl and 1 vol% HF for 10 min at 65 °C and then was placed in 30 vol% HNO 3 solution for 5 min. The chemical treatment is more effective on reducing ICR and improving corrosion resistance than that of electrochemical methods (be carried out in the 2 mol/L H 2 SO 4 solution with the electrical potential from −0.4 V to 0.6 V) for Fe–Ni–Cr alloy as a bipolar plate for polymer electrolyte membrane fuel cells. - Highlights: • The procedure of the surface treatments on Fe–Ni–Cr alloy as bipolar plate was described in detail. • Effects of various surface treatments on the interfacial contact resistivity and corrosion behavior were discussed. • The mechanism of the surface modification was particularly analyzed

  8. Characterization and corrosion behaviour of CoNi alloys obtained by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Olvera, S. [Instituto Politécnico Nacional, ESIQIE, Departamento de Ingeniería en Metalurgia y Materiales, México, D. F. (Mexico); Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química-Física Aplicada, 28049 Madrid (Spain); Sánchez-Marcos, J. [Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química-Física Aplicada, 28049 Madrid (Spain); Palomares, F.J. [Instituto de Ciencia de Materiales de Madrid, ICMM-CSIC, Cantoblanco, 28049 Madrid (Spain); Salas, E. [Spline Spanish CRG Beamline at the European Synchrotron Radiation Facilities, ESRF, BP 220-38043, Grenoble Cedex (France); Arce, E.M. [Instituto Politécnico Nacional, ESIQIE, Departamento de Ingeniería en Metalurgia y Materiales, México, D. F. (Mexico); Herrasti, P., E-mail: pilar.herrasti@uam.es [Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Química-Física Aplicada, 28049 Madrid (Spain)

    2014-07-01

    CoNi alloys including Co{sub 30}Ni{sub 70}, Co{sub 50}Ni{sub 50} and Co{sub 70}Ni{sub 30} were prepared via mechanical alloying using Co and Ni powders. The crystallinity and short-range order were studied using X-ray diffraction and X-ray absorption spectroscopy. The results show that the milling process increases the number of vacancies, especially around the Co atoms, while the milling time decreases the crystalline size and enhances the crystallinity. X-ray photoelectron spectroscopy was used to characterise the chemical composition of the samples surface. The magnetic properties were analysed using zero-field cooling, field cooling and a magnetic hysteresis loops. The magnetic saturation moment is approximately 1.05 μ{sub B}/atom; this value decreases with the mechanical alloying time, and it is proportional to the cobalt concentration. The polarization and impedance curves in different media (NaCl, H{sub 2}SO{sub 4} and NaOH) showed similar corrosion resistance values. The corrosion resistance increased in the order NaCl, H{sub 2}SO{sub 4} and NaOH. A good passivation layer was formed in NaOH due to the cobalt and nickel oxides on the particle surfaces. - Highlights: • Ni{sub x}Co{sub 100-x} alloys were synthesized by mechanical alloying • Milling time decrease size and enhances crystallinity. • Oxygen is not present in a significant percentage in bulk but is detected on the surface. • Magnetic saturation moment is 1.05 mB/atom and decrease with mechanical allowing time • Corrosion resistance is higher in NaOH than in NaCl or HCl solutions.

  9. [Corrosion resistance and wear resistance of Ni-Cr alloy after coating titanium nitride (TiN) in oral containing fluorine environment].

    Science.gov (United States)

    Weng, Wei-Min; Yu, Wei-Qiang; Shan, Wei-Lan; Zhang, Fu-Qiang

    2010-12-01

    The aim of this study was to evaluate the corrosion resistance and wear resistance of Ni-Cr alloy after coating titanium nitride (TiN) in oral containing fluorine environment. Physical vapor deposition was established to coat titanium nitride (TiN) on the surface of dental cast Ni-Cr alloy to form TiN/Ni-Cr compound. Both Ni-Cr alloy and TiN/Ni-Cr compound were exposed to 37 degrees centigrade, artificial saliva containing 0.24% NaF. The polarization curves of the specimens were measured by PARSTAT 2273 electrochemical station to investigate its corrosion resistance. Vicker's hardness was measured by HXD-1000TMC/LCD micro-hardness tester to investigate its wear resistance. Statistical analysis was performed by SAS 8.2 software package for Student's t methods. The corrosion potential of Ni-Cr alloy was -362.407 mV, the corrosion current density was 1.568μAcm(-2),the blunt-breaking potential was 426 mV bofor TiN coating. The corrosion potential of TiN/Ni-Cr compound was -268.638 mV, the corrosion current density was 0.114μAcm(-2),the blunt-breaking potential was 1142 mV after TiN coating. Polarization curves showed TiN/Ni-Cr compound improved the corrosion potential and blunt-breaking potential, decreased the corrosion current density. The Vicker's hardness of Ni-Cr alloy was 519.75±27.27 before TiN coating, the Vicker's hardness of TiN/Ni-Cr compound was 803.24±24.64, the D-value between them was 283.49±39.34. The difference of Vicker's harnesses between Ni-Cr alloy and TiN/Ni-Cr compound had significant (P<0.01). The results demonstrate that the TiN coating can improve the corrosion resistant to F-and the surface hardness of Ni-Cr alloy. Supported by Research Fund of Science and Technology Commission of Shanghai Municipality (Grant No.08DZ2271100), Shanghai Leading Academic Discipline Project (Grant No.S30206 ) and Research Fund of Health Bureau of Shanghai Municipality (Grant No.2009074).

  10. 9-12% Cr heat resistant steels. Alloy design, TEM characterisation of microstructure evolution and creep response at 650 C

    Energy Technology Data Exchange (ETDEWEB)

    Rojas Jara, David

    2011-03-21

    This work was carried out aiming to design and characterise 9-12% Cr steels with tailormade microstructures for applications in fossil fuel fired power plants. The investigations concentrated in the design and characterisation of heat resistant steels for applications in high oxidising atmospheres (12% Cr) and 9% Cr alloys for components such as rotors (P91). ThermoCalc calculations showed to be a reliable tool for alloy development. The modeling also provided valuable information for the adjustment of the processing parameters (austenisation and tempering temperatures). Two 12% Cr heat resistant steels with a fine dispersion of nano precipitates were designed and produced supported by thermodynamic modeling (ThermoCalc). A detailed characterisation of the microstructure evolution at different creep times (100 MPa / 650 C / 8000 h) was carried out by scanning transmission electron microscopy (STEM). The results of the microstructure analysis were correlated with the mechanical properties in order to investigate the influence of different precipitates (especially M{sub 23}C{sub 6} carbides) on the creep strength of the alloys. Precipitation of Laves phase and Z-phase was observed after several hundred hours creep time. Very few Z-phase of the type Cr(V,Ta)N nucleating from existing (V,Ta)(C,N) was observed. Both alloys show growth and coarsening of Laves phase, meanwhile the MX carbonitrides present a very slow growth and coarsening rate. Alloys containing Laves phase, MX and M{sub 23}C{sub 6} precipitates show best creep properties. The influence of hot-deformation and tempering temperature on the microstructure evolution on one of the designed 12% Cr alloys was studied during short-term creep at 80-250 MPa and 650 C. Quantitative determination of dislocation density and sub-grain size in the initial microstructure and after creep was investigated by STEM combined with the high-angle annular dark-field detector (HAADF). A correlation between microstructure

  11. 9-12% Cr heat resistant steels. Alloy design, TEM characterisation of microstructure evolution and creep response at 650 C

    International Nuclear Information System (INIS)

    Rojas Jara, David

    2011-01-01

    This work was carried out aiming to design and characterise 9-12% Cr steels with tailormade microstructures for applications in fossil fuel fired power plants. The investigations concentrated in the design and characterisation of heat resistant steels for applications in high oxidising atmospheres (12% Cr) and 9% Cr alloys for components such as rotors (P91). ThermoCalc calculations showed to be a reliable tool for alloy development. The modeling also provided valuable information for the adjustment of the processing parameters (austenisation and tempering temperatures). Two 12% Cr heat resistant steels with a fine dispersion of nano precipitates were designed and produced supported by thermodynamic modeling (ThermoCalc). A detailed characterisation of the microstructure evolution at different creep times (100 MPa / 650 C / 8000 h) was carried out by scanning transmission electron microscopy (STEM). The results of the microstructure analysis were correlated with the mechanical properties in order to investigate the influence of different precipitates (especially M 23 C 6 carbides) on the creep strength of the alloys. Precipitation of Laves phase and Z-phase was observed after several hundred hours creep time. Very few Z-phase of the type Cr(V,Ta)N nucleating from existing (V,Ta)(C,N) was observed. Both alloys show growth and coarsening of Laves phase, meanwhile the MX carbonitrides present a very slow growth and coarsening rate. Alloys containing Laves phase, MX and M 23 C 6 precipitates show best creep properties. The influence of hot-deformation and tempering temperature on the microstructure evolution on one of the designed 12% Cr alloys was studied during short-term creep at 80-250 MPa and 650 C. Quantitative determination of dislocation density and sub-grain size in the initial microstructure and after creep was investigated by STEM combined with the high-angle annular dark-field detector (HAADF). A correlation between microstructure evolution and creep

  12. Feasibility study of shape memory alloy ring spring systems for self-centring seismic resisting devices

    International Nuclear Information System (INIS)

    Fang, Cheng; Yam, Michael C H; Zhang, Yanyang; Lam, Angus C C

    2015-01-01

    Shape memory alloys (SMAs) have recently emerged as promising material candidates for structural seismic resisting purposes. Most of the existing SMA-based strategies, however, are based on the wire or rod form of SMAs, where issues such as gripping complexity and fracture may exist. This paper presents a proof-of-concept study on an innovative type of SMA-based self-centring system, namely, a superelastic SMA ring spring system. The proposed system includes a series of inner high-strength steel (HSS) rings and outer superelastic SMA rings stacked in alternation with mating taper faces, where the resisting load is provided by the wedging action which tends to expand the outer rings and concurrently to squeeze the inner rings. The superelastic effect of the SMA offers energy dissipation and a driving force for recentring, and the frictional effect over the taper face further contributes to the overall resisting load and energy dissipation. The feasibility of the new system is carefully examined via numerical studies considering the parameters of ring thickness, taper angle, and coefficient of friction. The key hysteretic responses, including resisting load, stiffness, stress distributions, source of residual deformation, energy dissipation, and equivalent viscous damping, are discussed in detail. The behaviour of the SMA ring springs is also studied via analytical models, and the analytical predictions are found to agree well with the numerical results. Finally, two practical applications of the new system, namely self-centring HS-SMA ring spring connections, and self-centring SMA ring spring dampers, are discussed via comprehensive numerical studies. (paper)

  13. Enhanced stress corrosion cracking resistance and electrical conductivity of a T761 treated Al-Zn-Mg-Cu alloy thin plate

    Science.gov (United States)

    Chen, Xu; Zhai, Sudan; Gao, Di; Liu, Ye; Xu, Jing; Liu, Yang

    2018-01-01

    The stress corrosion cracking (SCC) behavior, electrical conductivity and mechanical properties of an Al-Zn-Mg-Cu alloy pre-stretched thin plate for wing skin were researched in this paper. The microstructures and SCC fracture surfaces of the alloy treated at different conditions were characterized by transmission electron microscopy, optical microscopy and scanning electron microscopy. Results indicated that with the increasing of aging temperature, the electrical conductivity and the elongation increased greatly, while the strength decreased gradually which were closely associated with the type and morphology of the precipitates. Compared with the T6 treated alloy, the SCC resistance of the T761 treated Al-Zn-Mg-Cu alloy was improved greatly. The SCC behavior of the T6 treated alloy was dominated by anodic dissolution theory, whereas the hydrogen induced cracking controlled the fracture behavior of the T761 treated alloy which was influenced by the morphology of grain boundary precipitates in this investigated alloy.

  14. Oxidation resistant nanocrystalline MCrAl(Y) coatings and methods of forming such coatings

    Science.gov (United States)

    Cheruvu, Narayana S.; Wei, Ronghua

    2014-07-29

    The present disclosure relates to an oxidation resistant nanocrystalline coating and a method of forming an oxidation resistant nanocrystalline coating. An oxidation resistant coating comprising an MCrAl(Y) alloy may be deposited on a substrate, wherein M, includes iron, nickel, cobalt, or combinations thereof present greater than 50 wt % of the MCrAl(Y) alloy, chromium is present in the range of 15 wt % to 30 wt % of the MCrAl(Y) alloy, aluminum is present in the range of 6 wt % to 12 wt % of the MCrAl(Y) alloy and yttrium, is optionally present in the range of 0.1 wt % to 0.5 wt % of the MCrAl(Y) alloy. In addition, the coating may exhibit a grain size of 200 nm or less as deposited.

  15. An overview of NiTi shape memory alloy: Corrosion resistance and antibacterial inhibition for dental application

    Energy Technology Data Exchange (ETDEWEB)

    Fadlallah, Sahar A., E-mail: sahar.fadlallah@yahoo.com [Materials and Corrosion Lab. (MCL), Faculty of Science, Taif University, Taif (Saudi Arabia); Chemistry Department, Faculty of Science, Cairo University, Cairo (Egypt); El-Bagoury, Nader [Materials and Corrosion Lab. (MCL), Faculty of Science, Taif University, Taif (Saudi Arabia); Casting Technology Lab., Manufacturing Technology Dept., CMRDI, P.O. Box 87, Helwan, Cairo (Egypt); Gad El-Rab, Sanaa M.F. [Biotechnology Department, Faculty of Science, Taif University, Taif (Saudi Arabia); Botany Department, Faculty of Science, Asuit University, Asuit (Egypt); Ahmed, Rasha A. [Materials and Corrosion Lab. (MCL), Faculty of Science, Taif University, Taif (Saudi Arabia); Forensic Chemistry Laboratories, Medico Legal Department, Ministry of Justice, Cairo (Egypt); El-Ousamii, Ghaida [Materials and Corrosion Lab. (MCL), Faculty of Science, Taif University, Taif (Saudi Arabia)

    2014-01-15

    Highlights: • Evaluate the corrosion resistance of NiTi alloy by using electrochemical techniques. • Estimate the Antibacterial inhibition rate of NiTi alloy. • Assessment the mechanical properties of NiTi from the hardness measurements. • Comparsion the microstructures of cast NiTi with Ti, this indicate the role of Ni to change the behavior of alloy in oral environment. • Advise drinking green tea in small quantities in small quantities in the event of present NiTi alloy in the oral cavity. • Recommendation to use NiTi for dental application. -- Abstract: Nowadays, Nickel–titanium nearly equiatomic is considered as one of the best biomaterials. The aim of the present work deals with the evolution of the electrochemical behavior of NiTi in simulated oral environment. The hardness, microstructures corrosion resistance and antibacterial performance of NiTi alloy were compared with pure titanium. The hardness of NiTi is twice the hardness of pure titanium. Electrochemical techniques were used to detect the corrosion resistance of both biomaterials in Hank’s solution containing (−)-epigallocatechin gallate (EGCG) which used to simulate the oral environment. In the physiological solution selected for the present study, the impedance spectroscopy (EIS) results showed that EGCG sharply increase the corrosion resistance of NiTi from 129 kΩ cm{sup 2} to 1.10 T Ω cm{sup 2} while slowly increase the corrosion resistance of pure titanium from 9.4 kΩ cm{sup 2} to 11.3 kΩ cm{sup 2} during the duration time of immersion at 37 °C. The plate-counting method was used to evaluate the antibacterial performance against Staphylococcus aureus (ATCC 6538). Among the two specimens of biomaterials studied, the antibacterial performance results revealed that the NiTi alloy is better than the pure titanium. The morphology and chemical structure of NiTi and Ti samples were systematically investigated by scanning electron microscope (SEM) and energy dispersive X